EP1402037A1 - Pflanzengene, die am schutz gegen pathogene beteiligt sind - Google Patents
Pflanzengene, die am schutz gegen pathogene beteiligt sindInfo
- Publication number
- EP1402037A1 EP1402037A1 EP01940896A EP01940896A EP1402037A1 EP 1402037 A1 EP1402037 A1 EP 1402037A1 EP 01940896 A EP01940896 A EP 01940896A EP 01940896 A EP01940896 A EP 01940896A EP 1402037 A1 EP1402037 A1 EP 1402037A1
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- European Patent Office
- Prior art keywords
- plant
- gene
- expression
- nucleic acid
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
- C12Q1/6876—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes
- C12Q1/6888—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes for detection or identification of organisms
- C12Q1/6895—Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes for detection or identification of organisms for plants, fungi or algae
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07K—PEPTIDES
- C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
- C07K14/415—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from plants
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N15/00—Mutation or genetic engineering; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification; Use of hosts therefor
- C12N15/09—Recombinant DNA-technology
- C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
- C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
- C12N15/82—Vectors or expression systems specially adapted for eukaryotic hosts for plant cells, e.g. plant artificial chromosomes (PACs)
- C12N15/8241—Phenotypically and genetically modified plants via recombinant DNA technology
- C12N15/8261—Phenotypically and genetically modified plants via recombinant DNA technology with agronomic (input) traits, e.g. crop yield
- C12N15/8271—Phenotypically and genetically modified plants via recombinant DNA technology with agronomic (input) traits, e.g. crop yield for stress resistance, e.g. heavy metal resistance
- C12N15/8279—Phenotypically and genetically modified plants via recombinant DNA technology with agronomic (input) traits, e.g. crop yield for stress resistance, e.g. heavy metal resistance for biotic stress resistance, pathogen resistance, disease resistance
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q2600/00—Oligonucleotides characterized by their use
- C12Q2600/158—Expression markers
Definitions
- the present invention generally relates to the field of plant molecular biology, and more specifically to the regulation of gene expression in plants in response to pathogen exposure.
- Plants are capable of activating a large array of defense mechanisms in response to pathogen attack, some of which are preexisting and others are inducible.
- Pathogens must specialize to circumvent the defense mechanisms ofthe host, especially those biotrophic pathogens that derive their nutrition from an inthnate association with living plant cells. If the pathogen can cause disease, the interaction is said to be compatible, but if the plant is resistant, the interaction is said to be incompatible.
- a crucial factor determining the success of these mechanisms is the speed of their activation. Consequently, there is considerable interest in understanding how plants recognize pathogen attack and control expression of defense mechanisms.
- Some potential pathogens trigger a very rapid resistance response called gene-for-gene resistance.
- R gene specificity is generally quite narrow, in most cases only pathogens carrying a particular avr gene are recognized. Recognition is thought to be mediated by ligand-receptor binding. R genes have been studied extensively in recent years. For a review of R genes, see Ellis et al. (1998); Jones et al. (1997); and Ronald (1998).
- SA systemic acquired resistance
- the nature ofthe systemic signal that triggers SAR is a subject of debate (Shulaev et al., 1995; Vernooji et al., 1994).
- SA clearly moves from the site ofthe HR to other parts ofthe plant, but if this is the signal, it must be effective at extremely low concentration (Willitset et al., 1998).
- SAR is quite similar to some reactions that occur locally in response to attack by virulent (those that cause disease) or avirulent (those that trigger gene-for-gene resistance) pathogens.
- activation of defense gene expression occurs more slowly in response to virulent pathogens than in response to avirulent pathogens.
- Some pathogens trigger expression of defense genes tlirough a different signaling pathway that requires components of the jasmonic acid (JA) and ethylene signaling pathways (Creelman et al., 1997).
- NDRI and EDSl are required for gene-for-gene mediated resistance to avirulent strains ofthe bacterial pathogen Pseudomonas syringae and the oomycete pathogen Peronospora parasitica.
- ndrl mutants are susceptible to one set of avirulent pathogens, whereas edsl mutants are susceptible to a non-overlapping set (Aarts et el., 1998).
- the five cloned R genes that require EDSl all belong to the subset ofthe nucleotide binding site-leucine rich repeat (NBS-LRR) class of R genes that contain sequences similar to the cytoplasmic domains of Drosophila Toll and mammalian interleukin 1 transmembrane receptors (TIR-NBS-LRR).
- the two genes that require NDRI belong to the leucine-zipper (LZ-NBS-LRR) subclass of NBS-LRR genes.
- LZ-NBS-LRR leucine-zipper
- RPP8 that does not require EDSl or NDRI, so the correlation between R gene structure and requirement for EDSl or NDRI is not perfect. Nevertheless, these results show that R genes differ in their requirements for downstream factors and that these differences are correlated with R gene structural type.
- NDRI encodes a protein with two predicted transmembrane domains (Century et al. 1997).
- RPMI which requires NDRI to mediate resistance, is membrane-associated, despite the fact that its primary sequence does not include any likely membrane-integral stretches
- EDSl encodes a protein with blocks of homology to triacyl glycerol lipases (Falk et al, 1999). The significance of this homology is not known, but it is believed to speculate that EDSl is involved in synthesis or degradation of a signal molecule. EDSl expression is inducible by SA and pathogen infection, suggesting that EDSl may be involved in signal amplification (Falk et al., 1999).
- RPP7 and RPP8 were not significantly suppressed by mutations in either EDSl or NDRI, and that RPP7 resistance was also not compromised by mutations in EIN2, JAR1 or COI1, which affect ethylene or jasmonic acid signaling, or in coil /nprl or coil/NahG backgrounds.
- SA levels increase locally in response to pathogen attack, and systemically in response to the SAR-inducing signal.
- SA is necessary and sufficient for activation of PR gene expression and enhanced disease resistance.
- Physiological analyses and characterization of certain lesion-mimic mutants strongly suggest that there is a positive autoregulatory loop affecting SA concentrations (Shirasu et al., 1997; Hunt et al., 1997; Weymann et al., 1995).
- Several mutants with defects in SA signaling have been characterized. These include nprl, in which expression of Pi?
- cprl, cpr5, and cpr ⁇ which constitutively express PR genes
- the nprl suppressor ssil pad4, which has a defect in S A accumulation
- eds5 which has a defect in PRl expression.
- Expression ofthe defense genes PRl, BG2, and PR5 in response to SA treatment requires a gene called NPRl or NIM1. Mutations in nprl abolish SAR, and cause enhanced susceptibility to infection by various pathogens (Cao et al., 1994; Delaney et al., 1995; Glazebrook et al, 1996; Shah et al., 1997).
- NPRl appears to be a positive regulator of PP gene expression that acts downstream from SA.
- NPRl encodes a novel protein that contains ankyrin repeats (which are often involved in protein-protein interactions (Cao et al., 1997; Ryals et al., 1997), and that is localized to the nucleus in the presence of SA (Dong et al., 1998). Consequently, it is unlikely that NPRl acts as a transcription factor to directly control PR gene expression, but its nuclear localization suggests that it may interact with such transcription factors.
- PAD4 appears to act upstream from SA. ⁇ npad4 plants infected with a virulent P.
- ISR This phenomenon, called ISR, has been studied using Pseudomonas fluorescens strain WCS417r to colonize Arabidopsis roots (Pieterse et al., 1996). Colonized plants are more resistant to infection by the fungal pathogen Fusarium oxysporum f sp raphani and P. syringae (Pieterse et al., 1996). ISR occurs in nahG plants, indicating that it is not a SA-dependent phenomenon (Pieterse et al., 1996). Rather, ISR appears to be JA- and ethylene-dependent.
- NPRl mediates a resistance response characterized by PRl expression
- ISR signal if the SA-dependent signal is received, NPRl mediates a different resistance response. It is difficult to imagine how this could occur, unless NPRl is interacting with different 'adapter' molecules to mediate the different signals.
- the ankyrin repeats found in NPRl could function in protein-protein interactions between NPRl and adapter proteins. Identification of proteins that interact with NPRl, and characterization of plants with loss-of-function mutations affecting those proteins, would be very helpful for understanding how NPRl acts in each pathway. It would also be worthwhile to determine if the ssil or cpr ⁇ mutations suppress the ISR defect of nprl mutants. Relevance to disease resistance
- Overexpression of rate-limiting defense response regulators may cause the signaling network to respond faster or more strongly to pathogen attack, thereby improving resistance.
- overexpression of NPRl caused increased resistance to P. syringae and P. parasitica in a dosage dependent manner (Cao et al., 1998).
- NPP -overexpression had no obvious deleterious effects on plant growth, in contrast to mutations that lead to constitutive overexpression of defense responses, which generally cause dwarfism. Promoters for gene expression of plant pathogen defense genes
- Promoters (and other regulatory components) from bacteria, viruses, fungi and plants have been used to control gene expression in plant cells.
- Numerous plant transformation experiments using DNA constructs comprising various promoter sequences fused to various foreign genes have led to the identification of useful promoter sequences. It has been demonstrated that sequences up to 500-1,000 bases in most instances are sufficient to allow for the regulated expression of foreign genes. However, it has also been shown that sequences much longer than 1 kb may have useful features which permit high levels of gene expression in transgenic plants.
- the expression of genes encoding proteins that are useful for protecting plants from pathogen attack may have deleterious effects on plant growth if expressed constitutively.
- the invention generally provides an isolated nucleic acid molecule (polynucleotide) comprising a plant nucleotide sequence obtained or isolatable from a gene, the expression of which is altered, either increased or decreased, in response to pathogen infection.
- the plant nucleotide sequence comprises an open reading frame
- the plant nucleotide sequence comprises a promoter.
- a promoter sequence ofthe invention directs transcription of a linked nucleic acid segment, e.g., a linked plant DNA comprising an open reading frame for a stractural or regulatory gene, in a host cell, such as a plant cell, in response to pathogen infection of that cell.
- a "pathogen” includes bacteria, fungi, oomycetes, viruses, nematodes and insects, e.g., aphids (see Hammond-Kosack and Jones, 1997) .
- the expression of a plant nucleotide sequence of the invention comprising a promoter may be altered in response to one or more species of bacteria, nematode, fungi, oomycete, virus, or insect.
- the expression of a plant nucleotide sequence ofthe invention comprising an open reading frame may be useful to confer tolerance or resistance of a plant to one or more species of bacteria, nematode, fungi, oomycete, virus or insect.
- the nucleotide sequence preferably is obtained or isolatable from plant DNA.
- the nucleotide sequence is obtained or isolatable from a gene encoding a polypeptide which is substantially similar, and preferably has at least 70%, e.g., 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and even 90% or more, e.g., 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and 99%, amino acid sequence identity, to a polypeptide encoded by an Arabidopsis gene comprising any one of SEQ ID NOs: 1-953 and 2137-2661 or a fragment (portion) thereof which encodes a partial length polypeptide having substantially the same activity ofthe full-length polypeptide, a rice gene comprising one of SEQ ID NOs:2000-2129
- the present invention also provides an isolated nucleic acid molecule comprising a plant nucleotide sequence that directs transcription of a linked nucleic acid segment in a host cell, e.g., a plant cell.
- the nucleotide sequence preferably is obtained or isolatable from plant genomic DNA.
- the plant DNA is obtained or isolatable from a gene encoding a polypeptide which is substantially similar, and preferably has at least 10%, e.g., 71%), 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and even 90% or more, e.g., 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and 99%, amino acid sequence identity, to a polypeptide encoded by an Arabidopsis gene comprising any one of SEQ ID NOs: 1-953, a
- Prefened promoters comprise DNA obtained or isolatable from a gene encoding a polypeptide which is substantially similar, and preferably has at least 70%, e.g., 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and even 90% or more, e.g., 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and 99%, amino acid sequence identity, to a polypeptide encoded by an Arabidopsis gene comprising a promoter according to SEQ ID NOs:2137-2661, a rice gene comprising a promoter accordint to SEQ ID NOs:4738- 6813 or a fragment thereof (i.e., promoters isolatable from any one of SEQ ID NOs:2137-2661 or SEQ ID NOs:4738-6813
- the invention also provides uses for an isolated nucleic acid molecule, e.g., DNA or RNA, comprising a plant nucleotide sequence comprising an open reading frame encoding a polypeptide which is substantially similar, and preferably has at least 70%, e.g., 71%>, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and even 90% or more, e.g., 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and 99%, amino acid sequence identity, to a polypeptide encoded by an Arabidopsis, Chenopodium or rice gene comprising an open reading frame comprising any one of SEQ ID NOs: 1-953, 1954- 1966, 2000-2129, 2662-4737, or the complement thereof.
- these open reading frames may be useful to prepare plants that over- or under-express
- the promoters and open reading frames ofthe invention can be identified by any method. For example, they can be identified by employing an anay of nucleic acid samples, e.g., each sample having a plurality of oligonucleotides, and each plurality conesponding to a different plant gene, on a solid substrate, e.g., a DNA chip, and probes corresponding to nucleic acid which is up- or down-regulated in response to pathogen infection in one or more ecotypes or species of plant relative to a control (e.g., a water control, nucleic acid from an uninfected plant or nucleic acid from a mutant plant).
- a control e.g., a water control, nucleic acid from an uninfected plant or nucleic acid from a mutant plant.
- the Arabidopsis oligonucleotide probe anay consists of probes from about 8,100 unique Arabidopsis genes, which covers approximately one third ofthe genome. This genome array permits a broader, more complete and less biased analysis of gene expression.
- expression levels were determined by laser scanning and genes generally selected for expression levels that were > 2 fold over the control. For example, using this approach, 953 genes were identified, the expression of which was altered after infection of wild-type Arabidopsis plants with a pathogen (SEQ ID NOs: 1- 953).
- 81 encode regulatory factors (SEQ ID NOs: 39, 52, 60, 63, 81, 83, 106, 107, 115, 117, 118, 168, 174, 176, 179, 204, 207, 208, 220, 221, 248, 258, 268, 275, 280, 309, 323, 326, 329, 351, 419, 422, 429, 430, 432, 459, 460, 468, 469, 473, 500, 505, 506, 508, 529, 531, 533, 535, 538, 545, 553, 602, 606, 608, 610, 614, 616, 634, 654, 655, 684, 686, 687, 691, 717, 751, 752, 766, 777, 815, 831, 834, 835, 839, 841, 847, 876, 884, 906, 920, and 924).
- 333 genes were identified that are useful to confer improved resistance to plants to bacterial infection (SEQ ID NOs: 12-13, 18, 23, 36, 39-40, 43, 45, 50, 52, 57-58, 60-61, 64, 71-72, 81, 87-89, 97, 100, 102-105, 107, 111-112, 115, 119-120, 122, 125, 127-128, 140, 144, 148-150, 153, 165, 168-169, 176-177, 179, 183, 188, 191, 193-194, 197-198, 203-206, 208-209, 214, 219-222, 227, 230, 232, 237, 244-246, 248-249, 251-253, 258, 261, 264, 266, 268, 273-275, 283, 287, 290, 293, 297, 302, 305-306, 308, 312-315, 321- 322, 324, 326, 330, 333, 3
- pathogens that include bacteria, oomycetes and viruses (SEQ ID NOs: 12-13, 18, 23, 36, 39-40, 43, 45, 50, 52, 57-58, 60-61, 64, 71-72, 81, 87-88, 100, 102-105, 107, 111-112, 115, 119-120, 122, 125, 127-128, 140, 148- 150, 153, 168-169, 176-177, 188, 191, 193-194, 197-198, 203-206, 209, 219-222, 227, 232, 237, 244-246, 248-249, 251-253, 258, 261, 264, 266, 268, 273-275, 283, 287, 290, 293, 297, 302, 305-306, 308, 312-315, 324, 326, 330, 333, 341, 345, 353,
- genes SEQ ID NOs: 17, 70, 76, 81, 84, 109, 123, 144, 160, 230, 265, 268, 269, 271, 323, 333, 385, 427, 428, 430, 457, 505, 569, 597, 602, 606, 616, 708, 730, 741, 812, 862, and 942), the expression of which was elevated in an incompatible or a compatible interaction in four Arabidopsis ecotypes infected with bacteria. Eight ofthe genes were upregulated by 3 hours in an incompatible interaction, 18 ofthe genes were upregulated by 6 hours, but not at 3 hours, in an incompatible interaction, and 6 ofthe genes were upregulated in a compatible interaction.
- genes that were upregulated in response to infection e.g., bacterial or fungal infection, as well as 46 ofthe conesponding promoter containing regions, were identified.
- Thirty-six ofthe genes were upregulated in response to bacterial, e.g., Pseudomonas, infection (the promoters for genes conesponding to SEQ ID NOs: 104-106, 119, 123, 129, 131, 151-152, 183, 191, 198, 200, 227, 249, 274, 302, 358, 415, 481, 547, 566, 582, 628, 633, 639, 656, 673, 793, 818, 827, 864, 874, 880, and 904-905), while 23 ofthe genes were upregulated in response to fungal, e.g., Botrykis, infection (SEQ ID NOs: 18, 71, 119, 123, 129, 151, 191, 244, 245, 302,
- SEQ ID NOs:1001-1025 10 ofthe genes were upregulated only in response to fungal, e.g., Botrytis, infection (the promoters for genes conesponding to SEQ ID NOs: 18, 71, 244, 245, 545, 562, 637, 653, 747, 756, 774, and 842 are provided in SEQ ID NOs : 1026- 1035), and 11 genes were upregulated in response to both bacterial and fungal infection (the promoters for genes conesponding to SEQ ID NOs: 119, 123, 129, 151, 191, 302, 547, 566, 793, 864, and 905 are provided in SEQ ID NOs:1036-1046).
- 129 Arabidopsis genes (SEQ ID NOs: 3, 51, 54, 60, 61, 66, 75, 76, 78, 88, 95, 96, 101, 106, 108, 123, 126, 128, 129, 131, 137, 145-147, 150, 158, 169, 170, 172, 173, 197, 200, 216, 219, 224, 230, 233, 237, 249, 250, 263, 274, 275, 276, 299 ; 307, 323, 333, 342, 346, 359, 382, 383, 387, 391, 393, 401, 411, 415, 427, 442, 455, 459, 466 477, 481, 485, 487, 502, 511, 515, 525, 534, 539, 542, 560, 571, 577, 579, 584, 587, 595, 600 627, 638, 645, 654, 659, 668,
- nucleic acid molecules comprising a nucleotide sequence comprising an open reading frame expressed in response to pathogen infection comprising SEQ ID NOs:209, 216, 262, 267, 317, 386, 425, 440 and 800. These sequences are useful to over- or under-express the encoded product, or prepare knock-out plants which have an altered response to pathogen infection.
- the invention therefore provides a method in which the open reading frame of a plant pathogen resistance gene, e.g., a gene that is associated with a response to pathogen infection, which is altered in a plant in response to infection is identified and isolated.
- a transgene comprising the isolated open reading frame may be introduced to and expressed in a transgenic plant, e.g., prior to infection, e.g., constitutively, or early and/or rapidly after infection, or in regulatable (inducible) fashion, e.g., after exposure to a chemical or using a promoter that is upregulated after infection, so as to confer resistance to that transgenic plant to the pathogen relative to a conesponding plant which does not have the transgene.
- the expression ofthe transgene is preferably at higher than normal levels, and under the regulation of a promoter that allows very fast and high induction in response to the presence of a pathogen or under cycling promoters (e.g., circadian clock regulated promoters), such that the encoded gene product(s) is maintained at sufficiently high levels to provide enhanced resistance or tolerance.
- the invention further provides a method in which a gene in a plant which is downregulated in response to infection, is disrupted or the expression of that gene is further downregulated, e.g., using antisense expression, so as to result in a plant that has enhanced resistance to infection, and which disruption or downregulation preferably has little or no detrimental effect(s) on the host plant.
- plant strains that are more resistant to pathogens have a gene expression phenotype in which genes that are upregulated in response to infection are already expressed at a higher than normal basal level, and those genes that are downregulated are expressed at a lower than normal basal level.
- genes and promoters described hereinabove can be used to identify orthologous genes and their promoters which are also likely useful to enhance resistance of plants to pathogens. Moreover, the orthologous promoters are useful to express linked open reading frames. In addition by aligning the promoters of these orthologs, novel cis elements can be identified that are useful to generate synthetic promoters.
- the isolated nucleic acid molecules ofthe invention include the orthologs ofthe Arabidopsis, Chenopodium and rice sequences disclosed herein, i.e., the conesponding nucleic acid molecules in organisms other than Arabidopsis, Chenopodium and rice, including, but not limited to, plants other than Arabidopsis, Chenopodium and rice, preferably cereal plants, e.g., corn, wheat, rye, turfgrass, sorghum, millet, sugarcane, soybean, barley, alfalfa, sunflower, canola, soybean, cotton, peanut, tobacco, sugarbeet, or rice.
- cereal plants e.g., corn, wheat, rye, turfgrass, sorghum, millet, sugarcane, soybean, barley, alfalfa, sunflower, canola, soybean, cotton, peanut, tobacco, sugarbeet, or rice.
- An ortholog is a gene from a different species that encodes a product having the same function as the product encoded by a gene from a reference organism.
- Databases such GenBank or one found at http://bioserver.myongjiac.kr/rjce.htinl (for rice) may be employed to identify sequences related to the Arabidopsis or Chenopodium sequences, e.g., orthologs in cereal crops such as rice.
- recombinant DNA techniques such as hybridization or PCR may be employed to identify sequences related to the Arabidopsis sequences.
- the encoded ortholog products likely have at least 70% sequence identity to each other.
- the invention includes an isolated nucleic acid molecule comprising a nucleotide sequence encoding a polypeptide having at least 70% identity to a polypeptide encoded by one or more ofthe Arabidopsis, Chenopodium or rice sequences disclosed herein.
- promoter sequences within the scope ofthe invention are those which direct expression of an open reading frame which encodes a polypeptide that is substantially similar to an Arabidopsis polypeptide encoded by a gene comprising SEQ ID NOs: 1-953.
- genes and promoters described hereinabove can be used to identify orthologous genes and their promoters which are also likely expressed in a particular tissue and/or development manner. Moreover, the orthologous promoters are useful to express linked open reading frames. In addition, by aligning the promoters of these orthologs, novel cis elements can be identified that are useful to generate synthetic promoters.
- the isolated nucleic acid molecules ofthe invention include the orthologs ofthe Arabidopsis sequences disclosed herein, i.e., the conesponding nucleotide sequences in organisms other than Arabidopsis, including, but not limited to, plants other than Arabidopsis, preferably cereal plants, e.g., com, wheat, rye, turfgrass, sorghum, millet, sugarcane, soybean, barley, alfalfa, sunflower, canola, soybean, cotton, peanut, tobacco, sugarbeet, or rice.
- cereal plants e.g., com, wheat, rye, turfgrass, sorghum, millet, sugarcane, soybean, barley, alfalfa, sunflower, canola, soybean, cotton, peanut, tobacco, sugarbeet, or rice.
- orthologous gene is a gene from a different species that encodes a product having the same or similar function, e.g., catalyzing the same reaction as a product encoded by a gene from a reference organism.
- an ortholog includes polypeptides having less than, e.g., 65% amino acid sequence identity, but which ortholog encodes a polypeptide having the same or similar function.
- GenBank or one found at http://bioserver.myongjiac.kr/rjce.html (for rice) may be employed to identify sequences related to the Arabidopsis sequences, e.g., orthologs in cereal crops such as rice, wheat, sunflower or alfalfa.
- SEQ ID NOs: 6286 and 4210 are the rice promoter and open reading frame for rice peroxidase, the ortholog ofthe Arabidopsis gene comprising SEQ ID NO: 50.
- SEQ ID NOs: 3311, 5387, 3791 and 5867 are rice orthologs of the Arabidopsis gene comprising SEQ ID NO:609;
- SEQ ID NOs: 2699, 4775, 3463, 5539, 3584, 5660, 4451, 6527, 4595 and 6671 are rice orthologs of fhe Arabidopsis gene comprising SEQ ID NO: 139.
- the promoters ofthe invention include a consecutive stretch of about 25 to 2000, including 50 to 500 or 100 to 250, and up to 1000 or 1500, contiguous nucleotides, e.g., 40 to about 743, 60 to about 743, 125 to about 743, 250 to about 743, 400 to about 743, 600 to about 743, of any one of SEQ ID NOs:2137-2661, SEQ ID NOs:4738-6813 or the promoter orthologs thereof, which include the minimal promoter region.
- the nucleotide sequence that includes the promoter region includes at least one copy of a TATA box.
- the invention provides plant promoters, including orthologs of Arabidopsis promoters conesponding to genes comprising any one of SEQ ID NOs: 1-953.
- the present invention further provides a composition, an expression cassette or a recombinant vector containing the nucleic acid molecule ofthe invention, and host cells comprising the expression cassette or vector, e.g., comprising a plasmid.
- the present invention provides an expression cassette or a recombinant vector comprising a promoter ofthe invention linked to a nucleic acid segment which, when present in a plant, plant cell or plant tissue, results in transcription ofthe linked nucleic acid segment.
- nucleotide sequence is part of a gene which encodes a polypeptide having substantially the same stracture and function as a polypeptide encoded by a gene for the reference nucleotide sequence, e.g., the nucleotide sequence comprises a promoter from a gene that is the ortholog ofthe gene conesponding to the reference nucleotide sequence, as well as promoter sequences that are structurally related the promoter sequences particularly exemplified herein, i.e., the substantially similar promoter sequences hybridize to the complement ofthe promoter sequences exemplified herein under high or very high stringency conditions.
- substantially similar thus includes nucleotide sequences wherein the sequence has been modified, for example, to optimize expression in particular cells, as well as nucleotide sequences encoding a variant polypeptide comprising one or more amino acid substitutions relative to the (unmodified) polypeptide encoded by the reference sequence, which substitution(s) does not alter the activity ofthe variant polypeptide relative to the unmodified polypeptide.
- the term "substantially similar” when used herein with respect to polypeptide means that the polypeptide has substantially the same stracture and function as the reference polypeptide.
- the percentage of amino acid sequence identity between the substantially similar and the reference polypeptide is at least 65%, 66%, 67%, 68%, 69%, 70%, e.g., 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and even 90% or more, e.g., 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, up to at least 99%, wherein the reference polypeptide is a polypeptide encoded by an Arabidopsis gene comprising any one of SEQ ID NOs: 1-953, a
- Chenopodium gene comprising any one of SEQ ID NOs:1954-1966, or a rice gene comprising any one of SEQ ID NOs:2000-2129 or 2662-4737.
- an agent e.g., an antibody, which specifically binds to one ofthe polypeptides, specifically binds to the other.
- Sequence comparisons maybe canied out using a Smith- Waterman sequence alignment algorithm (see e.g., Waterman (1995) or http://www hto.usc.edu/software/seqaln/index.html).
- the localS program, version 1.16 is preferably used with following parameters: match: 1, mismatch penalty: 0.33, open-gap penalty: 2, extended-gap penalty: 2.
- nucleotide sequence that is "substantially similar" to a reference nucleotide sequence hybridizes to the reference nucleotide sequence in 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO 4 , 1 mM EDTA at 50°C with washing in 2X SSC, 0.1% SDS at 50°C, more desirably in 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO 4 , 1 mM EDTA at 50°C with washing in IX SSC, 0.1% SDS at 50°C, more desirably still in 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO 4 , 1 mM EDTA at 50°C with washing in 0.5X SSC, 0.1% SDS at 50°C, preferably in 7% sodium dodecyl sulfate (SDS), 0.5 MNaPO 4 , 1 mM EDTA at 50°C with
- the present invention further provides an expression cassette or a vector containing the nucleic acid molecule comprising an open reading frame ofthe invention operably linked to a promoter, or comprising a promoter ofthe invention operably linked to an open reading frame or portion thereof, and the vector may be a plasmid.
- cassettes or vectors when present in a plant, plant cell or plant tissue result in transcription ofthe linked nucleic acid fragment in the plant.
- the expression cassettes or vectors ofthe invention may optionally include other regulatory sequences, e.g., transcription terminator sequences, operator, repressor binding site, transcription factor binding site, and/or an enhancer and may be contained in a host cell.
- the expression cassette or vector may augment the genome of a transformed plant or may be maintained extrachromosomally.
- the expression cassette or vector may further have a Ti plasmid and be contained in an Agrobacterium tumefaciens cell; it may be carried on a microparticle, wherein the microparticle is suitable for ballistic transformation of a plant cell; or it may be contained in a plant cell or protoplast.
- the expression cassette can be contained in a transformed plant or cells thereof and the plant may be a dicot or a monocot. In particular, the plant may be a cereal plant.
- the invention also provides sense and anti-sense nucleic acid molecules conesponding to the open reading frames identified herein as well as their orthologs.
- expression cassettes e.g., recombinant vectors, and host cells, comprising the nucleic acid molecule ofthe invention, e.g., one which comprises a nucleotide sequence which encodes a polypeptide the expression of which is altered in response to pathogen infection.
- the present invention further provides a method of augmenting a plant genome by contacting plant cells with a nucleic acid molecule ofthe invention, e.g., one isolatable or obtained from a plant gene encoding a polypeptide that is substantially similar to a polypeptide encoded by an Arabidopsis, Chenopodium or rice gene comprising a sequence comprising any one of SEQ ID NOs: 1-953, 1954-1966, 2000-2129 or 2662-4737 so as to yield transformed plant cells; and regenerating the transformed plant cells to provide a differentiated transformed plant, wherein the differentiated transformed plant expresses the nucleic acid molecule in the cells ofthe plant.
- a nucleic acid molecule ofthe invention e.g., one isolatable or obtained from a plant gene encoding a polypeptide that is substantially similar to a polypeptide encoded by an Arabidopsis, Chenopodium or rice gene comprising a sequence comprising any one of SEQ ID NOs: 1-953, 1954-1966
- the nucleic acid molecule may be present in the nucleus, chloroplast, mitochondria and/or plastid ofthe cells ofthe plant.
- the present invention also provides a transgenic plant prepared by this method, a seed from such a plant and progeny plants from such a plant including hybrids and inbreds.
- Prefened transgenic plants are transgenic maize, soybean, barley, alfalfa, sunflower, canola, soybean, cotton, peanut, sorghum, tobacco, sugarbeet, rice, wheat, rye, turfgrass, millet, sugarcane, tomato, or potato.
- the invention also provides a method of plant breeding, e.g., to prepare a crossed fertile transgenic plant.
- the method comprises crossing a fertile transgenic plant comprising a particular nucleic acid molecule ofthe invention with itself or with a second plant, e.g., one lacking the particular nucleic acid molecule, to prepare the seed of a crossed fertile transgenic plant comprising the particular nucleic acid molecule.
- the seed is then planted to obtain a crossed fertile transgenic plant.
- the plant may be a monocot or a dicot.
- the plant is a cereal plant.
- the crossed fertile transgenic plant may have the particular nucleic acid molecule inherited through a female parent or through a male parent.
- the second plant may be an inbred plant.
- the crossed fertile transgenic may be a hybrid. Also included within the present invention are seeds of any of these crossed fertile transgenic plants.
- the various breeding steps are characterized by well-defined human intervention such as selecting the lines to be crossed, directing pollination ofthe parental lines, or selecting appropriate progeny plants. Depending on the desired properties different breeding measures are taken.
- the relevant techniques are well known in the art and include but are not limited to hybridization, inbreeding, backcross breeding, multiline breeding, variety blend, interspecific hybridization, aneuploid techniques, etc.
- Hybridization techniques also include the sterilization of plants to yield male or female sterile plants by mechanical, chemical or biochemical means. Cross pollination of a male sterile plant with pollen of a different line assures that the genome ofthe male sterile but female fertile plant will uniformly obtain properties of both parental lines.
- transgenic plants according to the invention can be used for the breeding of improved plant lines that for example increase the effectiveness of conventional methods such as herbicide or pesticide treatment or allow to dispense with said methods due to their modified genetic properties.
- new crops with improved stress tolerance can be obtained that, due to their optimized genetic "equipment", yield harvested product of better quality than products that were not able to tolerate comparable adverse developmental conditions.
- the nucleic acid molecules ofthe invention are: for open reading frames, useful to provide resistance to pathogens to alter expression of a particular gene conesponding to the open reading frame by decreasing or eliminating expression of that plant gene or by overexpressing a particular gene product, and as a diagnostic for the presence or absence ofthe pathogen by co ⁇ elating the expression level or pattern of expression of one or more of the nucleic acid molecules or polypeptides of the invention; and for promoters, useful to alter the expression of a linked open reading frame in response to pathogen infection.
- the invention includes isolated nucleic acid molecules that have increased expression in response to pathogen infection, the invention further provides compositions and methods for enhancing resistance to pathogen infection.
- compositions ofthe invention include plant nucleic acid sequences and the amino acid sequences for the polypeptides or partial-length polypeptides encoded thereby which are described herein, or other plant nucleic acid sequences and the amino acid sequences for the polypeptides or partial-length polypeptides encoded thereby which are operably linked to a promoters are useful to provide tolerance or resistance to a plant to a pathogen, preferably by preventing or inhibiting pathogen infection.
- Methods ofthe invention involve stably transforming a plant with one or more of at least a portion of these nucleotide sequences which confer tolerance or resistance operably linked to a promoter capable of driving expression of that nucleotide sequence in a plant cell.
- portion or fragment as it relates to a nucleic acid molecule, sequence or segment ofthe invention, when it is linked to other sequences for expression, is meant a sequence comprising at least 80 nucleotides, more preferably at least 150 nucleotides, and still more preferably at least 400 nucleotides. If not employed for expressing, a “portion” or “fragment” means at least 9, preferably 12, more preferably 15, even more preferably at least 20, consecutive nucleotides, e.g., probes and primers (oligonucleotides), conesponding to the nucleotide sequence ofthe nucleic acid molecules of the invention.
- resistant is meant a plant which exhibits substantially no phenotypic changes as a consequence of infection with the pathogen.
- tolerant is meant a plant which, although it may exhibit some phenotypic changes as a consequence of infection, does not have a substantially decreased reproductive capacity or substantially altered metabolism.
- a method of combating a pathogen in an agricultural crop comprises introducing to a plant, plant cell, or plant tissue an expression cassette comprising a nucleic acid molecule ofthe invention comprising an open reading frame so as to yield a transformed differentiated plant, transformed cell or transfonned tissue. Transformed cells or tissue can be regenerated to provide a transformed differentiated plant.
- the transformed differentiated plant preferably expresses the nucleic acid molecule in an amount that confers resistance to the transformed plant to pathogen infection relative to a conesponding nontransformed plant.
- the present invention also provides a transformed plant prepared by the method, progeny and seed thereof.
- tobacco mosaic virus cucumber mosaic virus
- turnip mosaic virus turnip vein clearing virus
- oilseed rape mosaic viras tobacco rattle viras
- pathogens within the scope ofthe invention include, but are not limited to, fungi such as Cochliobolus carbonum, Phytophthora infestans, Phytophthora sojae, Collesosichum, Melampsora lini, cladosporiumfulvum, Heminthosporium maydia, Peronospora parasitica, Puccinia sorghi, and Puccinia polysora; bacteria such as Phynchosporium secalis, Pseudomonas glycinea, Xanthomonas oryzae and, Fusarium oxyaporium; and nematodes such as Globodera rostochiensis.
- fungi such as Cochliobolus carbonum, Phytophthora infestans, Phytophthora sojae, Collesosichum, Melampsora lini, cladosporiumfulvum, Heminthosporium maydia
- the invention provides a nucleic acid molecule comprising a plant nucleotide sequence comprising at least a portion of a key effector gene(s) responsible for host resistance to particular pathogens.
- this sequence may be overexpressed individually, in the sense or antisense orientation, or in combination with other sequences to confer improved disease resistance or tolerance to a plant relative to a plant that does not comprise and/or express the sequence.
- the overexpression may be constitutive, or it may be preferable to express the effector gene(s) in a tissue-specific manner or from an inducible promoter including a promoter which is responsive to external stimuli, such as chemical application, or to pathogen infection, e.g., so as to avoid possible deleterious effects on plant growth if the effector gene(s) was constitutively expressed.
- the promoter employed may be one that is rapidly and transiently and/or highly transcribed after pathogen infection.
- a transfo ⁇ ned (transgenic) plant ofthe invention includes plants, the genome of which is augmented by a nucleic acid molecule ofthe invention, or in which the conesponding gene has been disrupted, e.g., to result in a loss, a decrease or an alteration, in the function ofthe product encoded by the gene, which plant may also have increased yields, e.g., under conditions of pathogen infection, and/or produce a better-quality product than the conesponding wild-type plant.
- the nucleic acid molecules ofthe invention are thus useful for targeted gene disraption, as well as markers and probes.
- the invention includes a pathogen, e.g., virus, tolerant or resistant plant and seed thereof having stably integrated and expressed within its genome, a nucleic acid molecule ofthe invention.
- the normal fertile transformed (transgenic) plant may be selfed to yield a substantially homogenous line with respect to viral resistance or tolerance. Individuals ofthe line, or the progeny thereof, may be crossed with plants which optionally exhibit the trait. In a particular embodiment ofthe method, the selfing and selection steps are repeated at least five times in order to obtain the homogenous (isogenic) line.
- the invention also provides transgenic plants and the products ofthe transgenic plants.
- the invention further includes a nucleotide sequence which is complementary to one (hereinafter "test" sequence) which hybridizes under low, moderate or stringent conditions with the nucleic acid molecules ofthe invention as well as RNA which is encoded by the nucleic acid molecule.
- test sequence a nucleotide sequence which is complementary to one (hereinafter "test" sequence) which hybridizes under low, moderate or stringent conditions with the nucleic acid molecules ofthe invention as well as RNA which is encoded by the nucleic acid molecule.
- either a denatured test or nucleic acid molecule ofthe invention is preferably first bound to a support and hybridization is effected for a specified period of time at a temperature of, e.g., between 55 and 70°C, in double strength citrate buffered saline (SC) containing 0.1%> SDS followed by rinsing ofthe support at the same temperature but with a buffer having a reduced SC concentration.
- SC citrate buffered saline
- SC citrate buffered saline
- a buffer having a reduced SC concentration buffers are typically single strength SC containing 0.1% SDS, half strength SC containing 0.1% SDS and one-tenth strength SC containing 0.1% SDS.
- the invention further provides a method to identify an open reading frame in the genome of a plant cell, the expression of which is altered by pathogen infection of that cell.
- the method comprises contacting a solid substrate comprising a plurality of samples comprising isolated plant nucleic acid of a probe comprising plant nucleic acid, e.g., cRNA, isolated from a pathogen infected plant so as to form a complex.
- Each individual sample comprises one or more nucleic acid sequences (e.g., oligonucleotides) corresponding to at least a portion of a plant gene.
- the method may be employed with nucleic acid samples and probes from any organism, e.g., any prokaryotic or eukaryotic organism.
- the nucleic acid sample and probes are from a plant, such as a dicot or monocot. More preferably the nucleic acid samples and probes are from a cereal plant. Even more preferably the nucleic acids and probes are from a crop plant.
- a second plurality of samples on a solid substrate, i.e., a DNA chip, each comprising a plurality of samples comprising isolated plant nucleic acid is contacted with a probe comprising plant nucleic acid isolated from an uninfected or infected control (mutant) plant so as to form a complex. Then complex formation between the samples and probes comprising nucleic acid from infected or control cells compared.
- Arabidopsis genes the expression of which is altered in response to infection by any of these viruses, can be identified. Regions that are 5N to the start codon for the gene can then be identified and/or isolated.
- the invention further provides a method for identifying a plant cell infected with a pathogen.
- the method comprises contacting nucleic acid obtained from a plant cell suspected of being infected with a pathogen with oligonucleotides conesponding to a portion of a plurality of sequences selected from SEQ ID NOs:l-953, 1954-1966, 2000-2129 or 2662-4737 under conditions effective to amplify those sequences. Then the presence ofthe amplified product is detected or detennined.
- each conesponding to two or more SEQ ID NOs: 1-953, 1954-1966, 2000- 2129, or 2662-4737 is indicative of pathogen infection.
- the invention further provides a method for identifying a plant cell infected with a pathogen.
- the method comprises contacting a protein sample obtained from a plant cell suspected of being infected with a pathogen with an agent that specifically binds a polypeptide encoded by an open reading frame comprising SEQ ID NOs:l-953, 1954-1966, 2000-2129 or 2662-4737 so as to form a complex. Then the presence or amount of complex formation is detected or determined.
- the invention provides an additional method for identifying a plant cell infected with a pathogen.
- the method comprises hybridizing a probe selected from SEQ ID NOs: 1-953, 1954- 1966, 2000-2129 or 2662-4737 to nucleic acid obtained from a plant cell suspected of being infected with a pathogen.
- the amount ofthe probe hybridized to nucleic acid obtained from a cell suspected of being infected with a viras is compared to hybridization ofthe probe to nucleic acid isolated from an uninfected cell.
- a change in the amount of at least two probes that hybridize to nucleic acid isolated from a cell suspected of being infected by a virus relative to hybridization of at least two probes to nucleic acid isolated from an uninfected cell is indicative of viral infection.
- a method to shuffle the nucleic acids ofthe invention involves fragmentation of a nucleic acid conesponding to a nucleic acid sequence listed in SEQ ID NOs: 1-953, 1954-1966, 2000-2129 or 2662-4737, the orthologs thereof, and the conesponding genes, followed by religation.
- This method allows for the production of polypeptides having altered activity relative to the native form ofthe polypeptide.
- the invention provides cells and transgenic plants containing nucleic acid segments produced through shuffling that encode polypeptides having altered activity relative to the conesponding native polypeptide.
- a computer readable medium containing the nucleic acid sequences ofthe invention as well as methods of use for the computer readable medium are provided.
- This medium allows a nucleic acid segment conesponding to a nucleic acid sequence listed in SEQ ID NOs: 1-953, 2137-2661, 1954-1966, 2000-2129, 2662-4737 or 4738-6813 to be used as a reference sequence to search against databases.
- This medium also allows for computer-based manipulation of a nucleic acid sequence conesponding to a nucleic acid sequence listed in SEQ ID NOs :l-953, 2137-2661, 1954-1966, 2000-2129, 2662-4737 or 4738-6813, and the conesponding gene and polypeptide encoded by the nucleic acid sequence.
- another embodiment ofthe present invention provides a method of using known inducers or inhibitors of genes identified as being important in plant-pathogen interactions to induce genes that are important in resistance, or to inhibit genes that are downregulated in resistance.
- some ofthe isolated nucleic acid molecules ofthe invention are useful in a method of combating a pathogen in an agricultural crop.
- the method comprises introducing to a plant an expression cassette comprising a nucleic acid molecule ofthe invention so as to yield a transformed differentiated plant.
- the transformed differentiated plant expresses the nucleic acid molecule in an amount that confers resistance to the transformed plant to infection relative to a corresponding nontransformed plant.
- genes include coding sequences and/or the regulatory sequences required for their expression.
- gene refers to a nucleic acid fragment that expresses mRNA or functional RNA, or encodes a specific protein, and which includes regulatory sequences.
- Genes also include nonexpressed DNA segments that, for example, form recognition sequences for other proteins.
- Genes can be obtained from a variety of sources, including cloning from a source of interest or synthesizing from known or predicted sequence information, and may include sequences designed to have desired parameters.
- mutant or wild type gene refers to a gene that is present in the genome of an untransformed cell, i.e., a cell not having a known mutation.
- a "marker gene” encodes a selectable or screenable trait.
- chimeric gene refers to any gene that contains 1) DNA sequences, including regulatory and coding sequences, that are not found together in nature, or 2) sequences encoding parts of proteins not naturally adjoined, or 3) parts of promoters that are not naturally adjoined. Accordingly, a chimeric gene may comprise regulatory sequences and coding sequences that are derived from different sources, or comprise regulatory sequences and coding sequences derived from the same source, but ananged in a manner different from that found in nature.
- transgene refers to a gene that has been introduced into the genome by transformation and is stably maintained.
- Transgenes may include, for example, genes that are either heterologous or homologous to the genes of a particular plant to be transformed. Additionally, transgenes may comprise native genes inserted into a non-native organism, or chimeric genes.
- endogenous gene refers to a native gene in its natural location in the genome of an organism.
- a “foreign” gene refers to a gene not normally found in the host organism but that is introduced by gene transfer.
- An "oligonucleotide” conesponding to a nucleotide sequence ofthe invention may be about 30 or fewer nucleotides in length (e.g., 9, 12, 15, 18, 20, 21 or 24, or any number between 9 and 30).
- Generally specific primers are upwards of 14 nucleotides in length.
- primers of 16 to 24 nucleotides in length may be prefened.
- probing can be done with entire restriction fragments ofthe gene disclosed herein which may be 100's or even lOOO's of nucleotides in length.
- the terms “protein,” “peptide” and “polypeptide” are used interchangeably herein.
- the nucleotide sequences ofthe invention can be introduced into any plant.
- the genes to be introduced can be conveniently used in expression cassettes for introduction and expression in any plant of interest.
- Such expression cassettes will comprise the transcriptional initiation region ofthe invention linked to a nucleotide sequence of interest.
- Prefened promoters include constitutive, tissue-specific, developmental-specific, inducible and/or viral promoters.
- Such an expression cassette is provided with a plurality of restriction sites for insertion ofthe gene of interest to be under the transcriptional regulation ofthe regulatory regions.
- the expression cassette may additionally contain selectable marker genes.
- the cassette will include in the 5'-3' direction of transcription, a transcriptional and translational initiation region, a DNA sequence of interest, and a transcriptional and translational termination region functional in plants.
- the termination region may be native with the transcriptional initiation region, may be native with the DNA sequence of interest, or may be derived from another source.
- Convenient termination regions are available from the Ti- plasmid of A. tumefaciens, such as the octopine synthase and nopaline synthase termination regions.
- Coding sequence refers to a DNA or RNA sequence that codes for a specific amino acid sequence and excludes the non-coding sequences. It may constitute an "uninterrupted coding sequence", i.e., lacking an intron, such as in a cDNA or it may include one or more introns bounded by appropriate splice junctions.
- An "intron” is a sequence of RNA which is contained in the primary transcript but which is removed through cleavage and re-ligation of the RNA within the cell to create the mature mRNA that can be translated into a protein.
- the te ⁇ ns "open reading frame” and “ORF” refer to the amino acid sequence encoded between translation initiation and termination codons of a coding sequence.
- initiation codon and “termination codon” refer to a unit of three adjacent nucleotides ('codon') in a coding sequence that specifies initiation and chain termination, respectively, of protein synthesis (mRNA translation).
- a “functional RNA” refers to an antisense RNA, ribozyme, or other RNA that is not translated.
- RNA transcript refers to the product resulting from RNA polymerase catalyzed transcription of a DNA sequence. When the RNA transcript is a perfect complementary copy ofthe DNA sequence, it is refened to as the primary transcript or it may be a RNA sequence derived from posttranscriptional processing ofthe primary transcript and is refened to as the mature RNA.
- Messenger RNA (mRNA) refers to the RNA that is without introns and that can be translated into protein by the cell.
- cDNA refers to a single- or a double-stranded DNA that is complementary to and derived from mRNA.
- regulatory sequences each refer to nucleotide sequences located upstream (5' non-coding sequences), within, or downstream (3' non-coding sequences) of a coding sequence, and which influence the transcription, RNA processing or stability, or translation ofthe associated coding sequence. Regulatory sequences include enhancers, promoters, translation leader sequences, introns, and polyadenylation signal sequences. They include natural and synthetic sequences as well as sequences which may be a combination of synthetic and natural sequences. As is noted above, the term “suitable regulatory sequences” is not limited to promoters.
- 5' non-coding sequence refers to a nucleotide sequence located 5' (upstream) to the coding sequence. It is present in the fully processed mRNA upstream ofthe initiation codon and may affect processing ofthe primary transcript to mRNA, mRNA stability or translation efficiency (Turner et al., 1995).
- 3' non-coding sequence refers to nucleotide sequences located 3' (downstream) to a coding sequence and include polyadenylation signal sequences and other sequences encoding regulatory signals capable of affecting mRNA processing or gene expression.
- the polyadenylation signal is usually characterized by affecting the addition of polyadenylic acid tracts to the 3' end ofthe mRNA precursor.
- the use of different 3' non-coding sequences is exemplified by Ingelbrecht et al., 1989.
- translation leader sequence refers to that DNA sequence portion of a gene between the promoter and coding sequence that is transcribed into RNA and is present in the fully processed mRNA upstream (5') ofthe translation start codon.
- the translation leader sequence may affect processing ofthe primary transcript to mRNA, mRNA stability or translation efficiency.
- mature protein refers to a post-translationally processed polypeptide without its signal peptide.
- Precursor protein refers to the primary product of translation of an mRNA.
- Signal peptide refers to the amino terminal extension of a polypeptide, which is translated in conjunction with the polypeptide forming a precursor peptide and which is required for its entrance into the secretory pathway.
- signal sequence refers to a nucleotide sequence that encodes the signal peptide.
- Intracellular localization sequence refers to a nucleotide sequence that encodes an intracellular targeting signal.
- An “intracellular targeting signal” is an amino acid sequence that is translated in conjunction with a protein and directs it to a particular subcellular compartment.
- Endoplasmic reticulum (ER) stop transit signal refers to a carboxy- terminal extension of a polypeptide, which is translated in conjunction with the polypeptide and causes a protein that enters the secretory pathway to be retained in the ER.
- ER stop transit sequence refers to a nucleotide sequence that encodes the ER targeting signal.
- Other intracellular targeting sequences encode targeting signals active in seeds and/or leaves and vacuolar targeting signals.
- “Pathogen” as used herein includes but is not limited to bacteria, fungi, yeast, oomycetes and viras, e.g., American wheat striate mosaic viras mosaic (A WSMV), barley stripe mosaic virus (BSMV), barley yellow dwarf virus (BYDV), Brome mosaic viras (BMV), cereal chlorotic mottle virus (CCMV), com chlorotic vein banding virus (CCVBV), maize chlorotic mottle virus (MCMV), maize dwarf mosaic virus (MDMV), A or B, wheat streak mosaic viras (WSMV), cucumber mosaic viras (CMV), cynodon chlorotic streak viras
- a WSMV American wheat striate mosaic viras mosaic
- BSMV barley stripe mosaic virus
- BYDV barley yellow dwarf virus
- BMV Brome mosaic viras
- CCMV cereal chlorotic mottle virus
- CCVBV com chlorotic vein banding virus
- MCMV maize chlor
- CCSV Chevron styrene-maleic anhydride virus
- JGMV Johnsongrass mosaic viras
- MVFV maize chlorotic mottle virus
- MDMV maize dwarf mosaic viras
- MRFV maize pellucid ringspot virus
- MRGV maize raya graesa virus
- MRFV maize rayado fino viras
- MRSV maize ring mottle virus
- MRCV maize rough dwarf virus
- MRDV maize sterile stunt virus
- strains of barley yellow striate viras maize streak virus
- MSV maize chlorotic stripe
- Bacterial pathogens include but are not limited to Pseudomonas avenae subsp. avenae, Xanthomonas campestris pv. holcicola, Enterobacter dissolvens, Erwinia dissolvens, Ervinia carotovora subsp. carotovora, Erwinia chrysanthemi pv. zeae, Pseudomonas andropogonis, Pseudomonas syringae pv. coronafaciens, Clavibacter michiganensis subsp., Corynebacterium michiganense pv.
- Fungal pathogens include but are not limited to Collelotrichum graminicola,
- Cephalosporium maydis, Helminthosporium pedicellatum (teleomo ⁇ h: Selosphaeriapedicellata), Cladosporium cladosporioides - Hormodendrum cladosporioides, C herbarum (teleomorph - Mycosphaerella tassiana), Cephalosporium maydis, A. Iternaria alternata, A. scochyta maydis, A. tritici, A.
- Exserohilum prolatum Drechslera prolata (teleomo ⁇ h: Setosphaeriaprolata), Graphium penicillioides, Leptosphaeria maydis, Leptothyrium zeae, Ophiosphaerella herpotricha (anamo ⁇ h - Scolecosporiella sp.), Pataphaeosphaeria michotii, Phoma sp., Septoria zeae, S. zeicola, S.
- Rhizoctonia solani minor A Iternaria alternala, Cercospora sorghi, Dictochaetaftrtilis, Fusarium acuminatum (teleomo ⁇ h Gihherella acuminata), E. equiseti (teleomo ⁇ h: G. intricans), E. oxysporum, E. pallidoroseum, E. poae, E. roseum, G cyanogena (anamo ⁇ h.- E. sulphureum), Microdochium holleyi, Mucor p., Periconia circinata, Phytophthora cactorum, P. drechsleri, P. nicotianae var.
- Smut Smut
- Stenocarpella macrospora Diplodia macrospora, Cercospora sorghi, Fusarium episphaeria, E. merismoides, F. oxysporum Schlechtend, E. poae, E. roseum, E. solani (teleomo ⁇ h: Nectria haematococca), F.
- Parasitic nematodes include but are not limited to Awl Dolichodorus spp., D. heterocephalus Bulb and stem (Europe), Ditylenchus dipsaci Burrowing Radopholus similis Cyst Heterodera avenae, H. zeae, Punctodera chalcoensis Dagger Xiphinema spp., X americanum, X meditenaneum False root-knot Nacobbus dorsalis Lance, Columbia Hoplolaimus columbus Lance Hoplolaimus spp., H. galeatus Lesion Pratylenchus spp., P. brachyuras, P. crenalus, P.
- Promoter refers to a nucleotide sequence, usually upstream (5') to its coding sequence, which controls the expression ofthe coding sequence by providing the recognition for RNA polymerase and other factors required for proper transcription.
- Promoter includes a minimal promoter that is a short DNA sequence comprised of a TATA box and other sequences that serve to specify the site of transcription initiation, to which regulatory elements are added for control of expression.
- Promoter also refers to a nucleotide sequence that includes a minimal promoter plus regulatory elements that is capable of controlling the expression of a coding sequence or functional RNA. This type of promoter sequence consists of proximal and more distal upstream elements, the latter elements often refened to as enhancers.
- an “enhancer” is a DNA sequence which can stimulate promoter activity and may be an innate element ofthe promoter or a heterologous element inserted to enhance the level or tissue specificity of a promoter. It is capable of operating in both orientations (no ⁇ nal or flipped), and is capable of functioning even when moved either upstream or downstream from the promoter. Both enhancers and other upstream promoter elements bind sequence-specific DNA-binding proteins that mediate their effects. Promoters may be derived in their entirety from a native gene, or be composed of different elements derived from different promoters found in nature, or even be comprised of synthetic DNA segments. A promoter may also contain DNA sequences that are involved in the binding of protein factors which control the effectiveness of transcription initiation in response to physiological or developmental conditions.
- the "initiation site” is the position su ⁇ ounding the first nucleotide that is part ofthe transcribed sequence, which is also defined as position +1. With respect to this site all other sequences ofthe gene and its controlling regions are numbered. Downstream sequences (i.e., further protein encoding sequences in the 3' direction) are denominated positive, while upstream sequences (mostly ofthe controlling regions in the 5' direction) are denominated negative.
- Promoter elements particularly a TATA element, that are inactive or that have greatly reduced promoter activity in the absence of upstream activation are refened to as "minimal or core promoters.”
- the minimal promoter functions to permit transcription.
- a “minimal or core promoter” thus consists only of all basal elements needed for transcription initiation, e.g., a TATA box and/or an initiator.
- Constant expression refers to expression using a constitutive or regulated promoter.
- Consditional and regulated expression refer to expression controlled by a regulated promoter.
- Constutive promoter refers to a promoter that is able to express the open reading frame (ORF) that it controls in all or nearly all ofthe plant tissues during all or nearly all developmental stages ofthe plant.
- ORF open reading frame
- Each ofthe transcription-activating elements do not exhibit an absolute tissue-specificity, but mediate transcriptional activation in most plant parts at a level of >1% ofthe level reached in the part ofthe plant in which transcription is most active.
- Regular promoter refers to promoters that direct gene expression not constitutively, but in a temporally- and/or spatially-regulated manner, and includes both tissue-specific and inducible promoters. It includes natural and synthetic sequences as well as sequences which may be a combination of synthetic and natural sequences. Different promoters may direct the expression of a gene in different tissues or cell types, or at different stages of development, or in response to different environmental conditions. New promoters of various types useful in plant cells are constantly being discovered, numerous examples may be found in the compilation by Okamuro et al. (1989).
- Typical regulated promoters useful in plants include but are not limited to safener-inducible promoters, promoters derived from the tetracyclme- inducible system, promoters derived from salicylate-inducible systems, promoters derived from alcohol-inducible systems, promoters derived from glucocorticoid-inducible system, promoters derived from pathogen-inducible systems, and promoters derived from ecdysome- inducible systems.
- tissue-specific promoter refers to regulated promoters that are not expressed in all plant cells but only in one or more cell types in specific organs (such as leaves or seeds), specific tissues (such as embryo or cotyledon), or specific cell types (such as leaf parenchyma or seed storage cells). These also include promoters that are temporally regulated, such as in early or late embryogenesis, during fruit ripening in developing seeds or fruit, in fully differentiated leaf, or at the onset of senescence.
- “Inducible promoter” refers to those regulated promoters that can be turned on in one or more cell types by an external stimulus, such as a chemical, light, hormone, stress, or a pathogen.
- “Operably-linked” refers to the association of nucleic acid sequences on single nucleic acid fragment so that the function of one is affected by the other.
- a regulatory DNA sequence is said to be “operably linked to” or “associated with” a DNA sequence that codes for an RNA or a polypeptide if the two sequences are situated such that the regulatory DNA sequence affects expression ofthe coding DNA sequence (i.e., that the coding sequence or functional RNA is under the transcriptional control ofthe promoter). Coding sequences can be operably-linked to regulatory sequences in sense or antisense orientation.
- “Expression” refers to the transcription and/or translation of an endogenous gene, ORF or portion thereof, or a transgene in plants.
- expression may refer to the transcription ofthe antisense DNA only.
- expression refers to the transcription and stable accumulation of sense (mRNA) or functional RNA. Expression may also refer to the production of protein.
- Specific expression is the expression of gene products which is limited to one or a few plant tissues (spatial limitation) and/or to one or a few plant developmental stages (temporal limitation). It is acknowledged that hardly a trae specificity exists: promoters seem to be preferably switch on in some tissues, while in other tissues there can be no or only little activity. This phenomenon is known as leaky expression. However, with specific expression in this invention is meant preferable expression in one or a few plant tissues.
- the "expression pattern" of a promoter is the pattern of expression levels which shows where in the plant and in what developmental stage transcription is initiated by said promoter. Expression patterns of a set of promoters are said to be complementary when the expression pattern of one promoter shows little overlap with the expression pattern ofthe other promoter.
- the level of expression of a promoter can be determined by measuring the 'steady state' concentration of a standard transcribed reporter mRNA. This measurement is indirect since the concentration ofthe reporter mRNA is dependent not only on its synthesis rate, but also on the rate with which the mRNA is degraded. Therefore, the steady state level is the product of synthesis rates and degradation rates.
- the rate of degradation can however be considered to proceed at a fixed rate when the transcribed sequences are identical, and thus this value can serve as a measure of synthesis rates.
- techniques available to those skilled in the art are hybridization SI -RNAse analysis, northern blots and competitive RT-PCR. This list of techniques in no way represents all available techniques, but rather describes commonly used procedures used to analyze transcription activity and expression levels of mRNA.
- the analysis of transcription start points in practically all promoters has revealed that there is usually no single base at which transcription starts, but rather a more or less clustered set of initiation sites, each of which accounts for some start points ofthe mRNA.
- a commonly used procedure to analyze expression patterns and levels is through determination ofthe 'steady state' level of protein accumulation in a cell.
- Commonly used candidates for the reporter gene known to those skilled in the art are 3-glucuronidase (GUS), chloramphenicol acetyl transferase (CAT) and proteins with fluorescent properties, such as green fluorescent protein (GFP) from Aequora victoria.
- GFP green fluorescent protein
- Detection systems can readily be created or are available which are based on, e.g., immunochemical, enzymatic, fluorescent detection and quantification. Protein levels can be determined in plant tissue extracts or in intact tissue using in situ analysis of protein expression.
- average expression is used here as the average level of expression found in all lines that do express detectable amounts of reporter gene, so leaving out ofthe analysis plants that do not express any detectable reporter mRNA or protein.
- Root expression level indicates the expression level found in protein extracts of complete plant roots. Likewise, leaf, and stem expression levels, are determined using whole extracts from leaves and stems. It is acknowledged however, that within each ofthe plant parts just described, cells with variable functions may exist, in which promoter activity may vary.
- Non-specific expression refers to constitutive expression or low level, basal ('leaky') expression in nondesired cells or tissues from a 'regulated promoter'.
- altered levels refers to the level of expression in transgenic organisms that differs from that of normal or untransformed organisms.
- “Overexpression” refers to the level of expression in transgenic cells or organisms that exceeds levels of expression in normal or untransformed (nontransgenic) cells or organisms.
- Antisense inhibition refers to the production of antisense RNA transcripts capable of suppressing the expression of protein from an endogenous gene or a transgene.
- Codon and transwitch each refer to the production of sense RNA transcripts capable of suppressing the expression of identical or substantially similar transgene or endogenous genes (U.S. Patent No. 5,231,020).
- Gene silencing refers to homology-dependent suppression of viral genes, transgenes, or endogenous nuclear genes. Gene silencing may be transcriptional, when the suppression is due to decreased transcription ofthe affected genes, or post-transcriptional, when the suppression is due to increased turnover (degradation) of RNA species homologous to the affected genes (English et al., 1996). Gene silencing includes virus-induced gene silencing (Ruiz et al. 1998). "Silencing suppressor” gene refers to a gene whose expression leads to counteracting gene silencing and enhanced expression of silenced genes. Silencing suppressor genes may be of plant, non-plant, or viral origin.
- heterologous DNA sequence refers to a sequence that originates from a source foreign to the particular host cell or, if from the same source, is modified from its original fo ⁇ n.
- a heterologous gene in a host cell includes a gene that is endogenous to the particular host cell but has been modified through, for example, the use of DNA shuffling.
- the terms also include non-naturally occuning multiple copies of a naturally occurring DNA sequence.
- the terms refer to a DNA segment that is foreign or heterologous to the cell, or homologous to the cell but in a position within the host cell nucleic acid in which the element is not ordinarily found. Exogenous DNA segments are expressed to yield exogenous polypeptides.
- a "homologous" DNA sequence is a DNA sequence that is naturally associated with a host cell into which it is introduced.
- “Homologous to” in the context of nucleotide sequence identity refers to the similarity between the nucleotide sequence of two nucleic acid molecules or between the amino acid sequences of two protein molecules. Estimates of such homology are provided by either DNA-DNA or DNA-RNA hybridization under conditions of stringency as is well understood by those skilled in the art (as described in Haines and Higgins (eds.), Nucleic Acid
- substantially similar refers to nucleotide and amino acid sequences that represent functional and/or stractural equivalents of Arabidopsis sequences disclosed herein.
- altered nucleotide sequences which simply reflect the degeneracy ofthe genetic code but nonetheless encode amino acid sequences that are identical to a particular amino acid sequence are substantially similar to the particular sequences.
- amino acid sequences that are substantially similar to a particular sequence are those wherein overall amino acid identity is at least 65% or greater to the instant sequences. Modifications that result in equivalent nucleotide or amino acid sequences are well within the routine skill in the art.
- nucleotide sequences encompassed by this invention can also be defined by their ability to hybridize, under low, moderate and/or stringent conditions (e.g., 0.1X SSC, 0.1% SDS, 65°C), with the nucleotide sequences that are within the literal scope ofthe instant claims.
- Target gene refers to a gene on the replicon that expresses the desired target coding sequence, functional RNA, or protein.
- the target gene is not essential for replicon replication.
- target genes may comprise native non- viral genes inserted into a non-native organism, or chimeric genes, and will be under the control of suitable regulatory sequences.
- the regulatory sequences in the target gene may come from any source, including the virus.
- Target genes may include coding sequences that are either heterologous or homologous to the genes of a particular plant to be transformed. However, target genes do not include native viral genes.
- target genes include, but are not limited to genes encoding a structural protein, a seed storage protein, a protein that conveys herbicide resistance, and a protein that conveys insect resistance. Proteins encoded by target genes are known as "foreign proteins”. The expression of a target gene in a plant will typically produce an altered plant trait.
- altered plant trait means any phenotypic or genotypic change in a transgenic plant relative to the wild-type or non-transgenic plant host.
- Transcription Stop Fragment refers to nucleotide sequences that contain one or more regulatory signals, such as polyadenylation signal sequences, capable of terminating transcription. Examples include the 3' non-regulatory regions of genes encoding nopaline synthase and the small subunit of ribulose bisphosphate carboxylase.
- Replication gene refers to a gene encoding a viral replication protein.
- the replication gene may also contain other overlapping or non-overlapping ORF(s), as are found in viral sequences in nature. While not essential for replication, these additional ORFs may enhance replication and/or viral DNA accumulation. Examples of such additional ORFs are AC3 and AL3 in ACMV and TGMV geminivirases, respectively.
- Chimeric trans-ac ⁇ ng replication gene refers either to a replication gene in which the coding sequence of a replication protein is under the control of a regulated plant promoter other than that in the native viral replication gene, or a modified native viral replication gene, for example, in which a site specific sequence(s) is inserted in the 5' transcribed but untranslated region.
- Such chimeric genes also include insertion ofthe known sites of replication protein binding between the promoter and the transcription start site that attenuate transcription of viral replication protein gene.
- Chrosomally-integrated refers to the integration of a foreign gene or DNA construct into the host DNA by covalent bonds. Where genes are not “chromosomally integrated” they may be “transiently expressed.” Transient expression of a gene refers to the expression of a gene that is not integrated into the host chromosome but functions independently, either as part of an autonomously replicating plasmid or expression cassette, for example, or as part of another biological system such as a virus.
- Production tissue refers to mature, harvestable tissue consisting of non-dividing, terminally-differentiated cells. It excludes young, growing tissue consisting of germline, meristematic, and not-fully-differentiated cells.
- Ge ⁇ nline cells refer to cells that are destined to be gametes and whose genetic material is heritable.
- Trans-activation refers to switching on of gene expression or replicon replication by the expression of another (regulatory) gene in trans.
- transformation refers to the transfer of a nucleic acid fragment into the genome of a host cell, resulting in genetically stable inheritance.
- Host cells containing the transformed nucleic acid fragments are refened to as "transgenic” cells, and organisms comprising transgenic cells are refened to as "transgenic organisms".
- transgenic organisms examples include Agrobacterium-mediated transformation (De Blaere et al., 1987) and particle bombardment technology (Klein et al. 1987; U.S. Patent No. 4,945,050).
- Whole plants may be regenerated from transgenic cells by methods well known to the skilled artisan (see, for example, Fromm et al., 1990).
- Transformed refers to a host organism such as a bacterium or a plant into which a heterologous nucleic acid molecule has been introduced.
- the nucleic acid molecule can be stably integrated into the genome generally known in the art and are disclosed in Sambrook et al, 1989. See also Innis et al., 1995 and Gelfand, 1995; and Innis and Gelfand, 1999.
- Known methods of PCR include, but are not limited to, methods using paired primers, nested primers, single specific primers, degenerate primers, gene-specific primers, vector-specific primers, partially mismatched primers, and the like.
- “transformed,” “transformant,” and “transgenic” plants or calli have been tlirough the transformation process and contain a foreign gene integrated into their chromosome.
- the term “untransformed” refers to normal plants that have not been through the transformation process.
- Transiently transformed refers to cells in which transgenes and foreign DNA have been introduced (for example, by such methods as Agrobacterium-mediated transformation or biolistic bombardment), but not selected for stable maintenance.
- “Stably transformed” refers to cells that have been selected and regenerated on a selection media following transformation.
- Transient expression refers to expression in cells in which a virus or a transgene is introduced by viral infection or by such methods as Agrobacterium-mediated transformation, electroporation, or biolistic bombardment, but not selected for its stable maintenance.
- Genetically stable and “heritable” refer to chromosomally-integrated genetic elements that are stably maintained in the plant and stably inherited by progeny tlirough successive generations.
- Primary transformant and “TO generation” refer to transgenic plants that are ofthe same genetic generation as the tissue which was initially transformed (i.e., not having gone tlirough meiosis and fertilization since transformation).
- Secondary transformants and the “TI, T2, T3, etc. generations” refer to transgenic plants derived from primary transformants through one or more meiotic and fertilization cycles. They may be derived by self-fertilization of primary or secondary transformants or crosses of primary or secondary transformants with other transformed or untransformed plants.
- Wild-type refers to a viras or organism found in nature without any known mutation.
- Gene refers to the complete genetic material of an organism.
- nucleic acid refers to deoxyribonucleotides or ribonucleotides and polymers thereof in either single- or double-stranded form, composed of monomers (nucleotides) containing a sugar, phosphate and a base which is either a purine or pyrimidine. Unless specifically limited, the term encompasses nucleic acids containing known analogs of natural nucleotides which have similar binding properties as the reference nucleic acid and are metabolized in a manner similar to naturally occuning nucleotides.
- nucleic acid sequence also implicitly encompasses conservatively modified variants thereof (e.g., degenerate codon substitutions) and complementary sequences as well as the sequence explicitly indicated.
- degenerate codon substitutions may be achieved by generating sequences in which the third position of one or more selected (or all) codons is substituted with mixed-base and/or deoxyinosine residues (Batzer et al., 1991; Ohtsuka et al., 1985; Rossolini et al. 1994).
- a "nucleic acid fragment" is a fraction of a given nucleic acid molecule.
- nucleotide sequence refers to a polymer of DNA or RNA which can be single- or double-stranded, optionally containing synthetic, non-natural or altered nucleotide bases capable of inco ⁇ oration into DNA or RNA polymers.
- an "isolated” or “purified” DNA molecule or an “isolated” or “purified” polypeptide is a DNA molecule or polypeptide that, by the hand of man, exists apart from its native environment and is therefore not a product of nature.
- An isolated DNA molecule or polypeptide may exist in a purified form or may exist in a non-native environment such as, for example, a transgenic host cell.
- an "isolated” or “purified” nucleic acid molecule or protein, or biologically active portion thereof is substantially free of other cellular material, or culture medium when produced by recombinant techniques, or substantially free of chemical precursors or other chemicals when chemically synthesized.
- an "isolated" nucleic acid is free of sequences (preferably protein encoding sequences) that naturally flank the nucleic acid (i.e., sequences located at the 5' and 3' ends ofthe nucleic acid) in the genomic DNA ofthe organism from which the nucleic acid is derived.
- the isolated nucleic acid molecule can contain less than about 5 kb, 4 kb, 3 kb, 2 kb, 1 kb, 0.5 kb, or 0.1 kb of nucleotide sequences that naturally flank the nucleic acid molecule in genomic DNA ofthe cell from which the nucleic acid is derived.
- a protein that is substantially free of cellular material includes preparations of protein or polypeptide having less than about 30%, 20%, 10%, 5%, (by dry weight) of contaminating protein.
- culture medium represents less than about 30%), 20%), 10%), or 5% (by dry weight) of chemical precursors or non-protein of interest chemicals.
- nucleotide sequences ofthe invention include both the naturally occurring sequences as well as mutant (variant) forms. Such variants will continue to possess the desired activity, i.e., either promoter activity or the activity ofthe product encoded by the open reading frame ofthe non- variant nucleotide sequence.
- variants are intended substantially similar sequences.
- variants include those sequences that, because of the degeneracy ofthe genetic code, encode the identical amino acid sequence ofthe native protein.
- Naturally occuning allelic variants such as these can be identified with the use of well-known molecular biology techniques, as, for example, with polymerase chain reaction (PCR) and hybridization techniques.
- variant nucleotide sequences also include synthetically derived nucleotide sequences, such as those generated, for example, by using site-directed mutagenesis and for open reading frames, encode the native protein, as well as those that encode a polypeptide having amino acid substitutions relative to the native protein.
- nucleotide sequence variants ofthe invention will have at least 40, 50, 60, to 70%, e.g., preferably 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, to 79%, generally at least 80%, e.g., 81%-84%, at least 85%, e.g., 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%o, to 98%> and 99%) nucleotide sequence identity to the native (wild type or endogenous) nucleotide sequence.
- Consatively modified variations of a particular nucleic acid sequence refers to those nucleic acid sequences that encode identical or essentially identical amino acid sequences, or where the nucleic acid sequence does not encode an amino acid sequence, to essentially identical sequences. Because ofthe degeneracy ofthe genetic code, a large number of functionally identical nucleic acids encode any given polypeptide. For instance the codons CGT, CGC, CGA, CGG, AGA, and AGG all encode the amino acid arginine. Thus, at every position where an arginine is specified by a codon, the codon can be altered to any ofthe conesponding codons described without altering the encoded protein.
- nucleic acid variations are "silent variations" which are one species of “conservatively modified variations.” Every nucleic acid sequence described herein which encodes a polypeptide also describes every possible silent variation, except where otherwise noted.
- each codon in a nucleic acid except ATG, which is ordinarily the only codon for methionine
- each "silent variation" of a nucleic acid which encodes a polypeptide is implicit in each described sequence.
- the nucleic acid molecules ofthe invention can be "optimized" for enhanced expression in plants of interest. See, for example, EPA 035472; WO 91/16432; Perlak et al., 1991; and Murray et al., 1989. In this manner, the open reading frames in genes or gene fragments can be synthesized utilizing plant-prefened codons. See, for example, Campbell and Gowri, 1990 for a discussion of host-prefened codon usage.
- the nucleotide sequences can be optimized for expression in any plant. It is recognized that all or any part of the gene sequence may be optimized or synthetic. That is, synthetic or partially optimized sequences may also be used.
- Variant nucleotide sequences and proteins also encompass sequences and protein derived from a mutagenic and recombinogenic procedure such as DNA shuffling. With such a procedure, one or more different coding sequences can be manipulated to create a new polypeptide possessing the desired properties. In this manner, libraries of recombinant polynucleotides are generated from a population of related sequence polynucleotides comprising sequence regions that have substantial sequence identity and can be homologously recombined in vitro or in vivo. Strategies for such DNA shuffling are known in the art.
- variant polypeptide is intended a polypeptide derived from the native protein by deletion (so-called truncation) or addition of one or more amino acids to the N-terminal and/or C-terminal end ofthe native protein; deletion or addition of one or more amino acids at one or more sites in the native protem; or substitution of one or more amino acids at one or more sites in the native protein.
- variants may result from, for example, genetic polymo ⁇ hism or from human manipulation. Methods for such manipulations are generally known in the art.
- polypeptides may be altered in various ways including amino acid substitutions, deletions, truncations, and insertions. Methods for such manipulations are generally known in the art.
- amino acid sequence variants ofthe polypeptides can be prepared by mutations in the DNA. Methods for mutagenesis and nucleotide sequence alterations are well known in the art. See, for example, Kunkel, 1985; Kunkel et al., 1987; U. S. Patent No. 4,873,192; Walker and Gaastra, 1983 and the references cited therein.
- Guidance as to appropriate amino acid substitutions that do not affect biological activity ofthe protein of interest may be found in the model of Dayhoff et al. (1978). Conservative substitutions, such as exchanging one amino acid with another having similar properties, are prefened.
- “Expression cassette” as used herein means a DNA sequence capable of directing expression of a particular nucleotide sequence in an appropriate host cell, comprising a promoter operably linked to the nucleotide sequence of interest which is operably linked to termination signals. It also typically comprises sequences required for proper translation ofthe nucleotide sequence.
- the coding region usually codes for a protein of interest but may also code for a functional RNA of interest, for example antisense RNA or a nontranslated RNA, in the sense or antisense direction.
- the expression cassette comprising the nucleotide sequence of interest may be chimeric, meaning that at least one of its components is heterologous with respect to at least one of its other components.
- the expression cassette may also be one which is naturally occurring but has been obtained in a recombinant form useful for heterologous expression.
- the expression ofthe nucleotide sequence in the expression cassette may be under the control of a constitutive promoter or of an inducible promoter which initiates transcription only when the host cell is exposed to some particular external stimulus.
- the promoter can also be specific to a particular tissue or organ or stage of development.
- Vector is defined to include, inter alia, any plasmid, cosmid, phage or Agrobacterium binary vector in double or single stranded linear or circular form which may or may not be self transmissible or mobilizable, and which can transform prokaryotic or eukaryotic host either by integration into the cellular genome or exist extrachromosomally (e.g. autonomous replicating plasmid with an origin of replication).
- shuttle vectors by which is meant a DNA vehicle capable, naturally or by design, of replication in two different host organisms, which may be selected from actinomycetes and related species, bacteria and eukaryotic (e.g. higher plant, mammalian, yeast or fungal cells).
- the nucleic acid in the vector is under the control of, and operably linked to, an appropriate promoter or other regulatory elements for transcription in a host cell such as a microbial, e.g. bacterial, or plant cell.
- a host cell such as a microbial, e.g. bacterial, or plant cell.
- the vector may be a bi-functional expression vector which functions in multiple hosts. In the case of genomic DNA, this may contain its own promoter or other regulatory elements and in the case of cDNA this may be under the control of an appropriate promoter or other regulatory elements for expression in the host cell.
- Codoning vectors typically contain one or a small number of restriction endonuclease recognition sites at which foreign DNA sequences can be inserted in a determinable fashion without loss of essential biological function ofthe vector, as well as a marker gene that is suitable for use in the identification and selection of cells transformed with the cloning vector. Marker genes typically include genes that provide tetracycline resistance, hygromycin resistance or ampicillin resistance.
- a "transgenic plant” is a plant having one or more plant cells that contain an expression vector.
- Plant tissue includes differentiated and undifferentiated tissues or plants, including but not limited to roots, stems, shoots, leaves, pollen, seeds, tumor tissue and various forms of cells and culture such as single cells, protoplast, embryos, and callus tissue.
- the plant tissue may be in plants or in organ, tissue or cell culture.
- sequence relationships between two or more nucleic acids or polynucleotides are used to describe the sequence relationships between two or more nucleic acids or polynucleotides: (a) “reference sequence”, (b) “comparison window”, (c) “sequence identity”, (d) “percentage of sequence identity”, and (e) “substantial identity”.
- reference sequence is a defined sequence used as a basis for sequence comparison.
- a reference sequence may be a subset or the entirety of a specified sequence; for example, as a segment of a full length cDNA or gene sequence, or the complete cDNA or gene sequence.
- comparison window makes reference to a contiguous and specified segment of a polynucleotide sequence, wherein the polynucleotide sequence in the comparison window may comprise additions or deletions (i.e., gaps) compared to the reference sequence (which does not comprise additions or deletions) for optimal alignment ofthe two sequences.
- the comparison window is at least 20 contiguous nucleotides in length, and optionally can be 30, 40, 50, 100, or longer.
- Such implementations include, but are not limited to: CLUSTAL in the PC/Gene program (available from Intelligenetics, Mountain View, California); the ALIGN program (Version 2.0) and GAP, BESTFIT, BLAST, FASTA, and TFASTA in the Wisconsin Genetics Software Package, Version 8 (available from Genetics Computer Group (GCG), 575 Science Drive, Madison, Wisconsin, USA). Alignments using these programs can be performed using the default parameters.
- the CLUSTAL program is well described by Higgins et al. 1988; Higgins et al. 1989; Co ⁇ et et al. 1988; Huang et al. 1992; and Pearson et al. 1994.
- the ALIGN program is based on the algorithm of Myers and Miller, supra.
- the BLAST programs of Altschul et al., 1990, are based on the algorithm of Karlin and Altschul supra .
- HSPs high scoring sequence pairs
- Cumulative scores are calculated using, for nucleotide sequences, the parameters M (reward score for a pair of matching residues; always > 0) and N (penalty score for mismatching residues; always ⁇ 0).
- M forward score for a pair of matching residues
- N penalty score for mismatching residues; always ⁇ 0.
- a scoring matrix is used to calculate the cumulative score. Extension ofthe word hits in each direction are halted when the cumulative alignment score falls off by the quantity X from its maximum achieved value, the cumulative score goes to zero or below due to the accumulation of one or more negative-scoring residue alignments, or the end of either sequence is reached.
- the BLAST algorithm In addition to calculating percent sequence identity, the BLAST algorithm also performs a statistical analysis ofthe similarity between two sequences (see, e.g., Karlin & Altschul (1993).
- One measure of similarity provided by the BLAST algorithm is the smallest sum probability (P(N)), which provides an indication ofthe probability by which a match between two nucleotide or amino acid sequences would occur by chance.
- P(N) the smallest sum probability
- a test nucleic acid sequence is considered similar to a reference sequence if the smallest sum probability in a comparison ofthe test nucleic acid sequence to the reference nucleic acid sequence is less than about 0.1, more preferably less than about 0.01, and most preferably less than about 0.001.
- Gapped BLAST in BLAST 2.0
- PSI-BLAST in BLAST 2.0
- the default parameters ofthe respective programs e.g. BLASTN for nucleotide sequences, BLASTX for proteins
- W wordlength
- E expectation
- BLASTP program uses as defaults a wordlength (W) of 3, an expectation (E) of 10, and the BLOSUM62 scoring matrix (see Henikoff & Henikoff, 1989). See http://www.ncbi.nlm.nih.gov. Alignment may also be performed manually by inspection.
- comparison of nucleotide sequences for determination of percent sequence identity to the promoter sequences disclosed herein is preferably made using the BlastN program (version 1.4.7 or later) with its default parameters or any equivalent program.
- equivalent program is intended any sequence comparison program that, for any two sequences in question, generates an alignment having identical nucleotide or amino acid residue matches and an identical percent sequence identity when compared to the conesponding alignment generated by the prefened program.
- sequence identity or “identity” in the context of two nucleic acid or polypeptide sequences makes reference to the residues in the two sequences that are the same when aligned for maximum conespondence over a specified comparison window.
- sequence similarity or “similarity.” Means for making this adjustment are well known to those of skill in the art. Typically this involves scoring a conservative substitution as a partial rather than a full mismatch, thereby increasing the percentage sequence identity.
- percentage of sequence identity means the value determined by comparing two optimally aligned sequences over a comparison window, wherein the portion of the polynucleotide sequence in the comparison window may comprise additions or deletions (i.e., gaps) as compared to the reference sequence (which does not comprise additions or deletions) for optimal alignment ofthe two sequences. The percentage is calculated by determining the number of positions at which the identical nucleic acid base or arnino acid residue occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison, and multiplying the result by 100 to yield the percentage of sequence identity.
- polynucleotide sequences means that a polynucleotide comprises a sequence that has at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, or 79%, preferably at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, or 89%, more preferably at least 90%, 91%, 92%, 93%, or 94%, and most preferably at least 95%, 96%, 97%, 98%, or 99% sequence identity, compared to a reference sequence using one ofthe aligmnent programs described using standard parameters.
- Substantial identity of amino acid sequences for these pu ⁇ oses normally means sequence identity of at least 10%, more preferably at least 80%, 90%, and most preferably at least 95%.
- nucleotide sequences are substantially identical if two molecules hybridize to each other under stringent conditions (see below).
- stringent conditions are selected to be about 5°C lower than the thermal melting point (T m ) for the specific sequence at a defined ionic strength and pH.
- T m thermal melting point
- stringent conditions encompass temperatures in the range of about 1°C to about 20°C, depending upon the desired degree of stringency as otherwise qualified herein.
- Nucleic acids that do not hybridize to each other under stringent conditions are still substantially identical if the polypeptides they encode are substantially identical. This may occur, e.g., when a copy of a nucleic acid is created using the maximum codon degeneracy permitted by the genetic code.
- One indication that two nucleic acid sequences are substantially identical is when the polypeptide encoded by the first nucleic acid is immunologically cross reactive with the polypeptide encoded by the second nucleic acid.
- substantially identical in the context of a peptide indicates that a peptide comprises a sequence with at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, or 79%, preferably 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, or 89%, more preferably at least 90%, 91%, 92%, 93%, or 94%, or even more preferably, 95%, 96%, 97%, 98% or 99%, sequence identity to the reference sequence over a specified comparison window.
- optimal alignment is conducted using the homology alignment algorithm of Needleman and Wunsch (1970).
- a peptide is substantially identical to a second peptide, for example, where the two peptides differ only by a conservative substitution.
- sequence comparison typically one sequence acts as a reference sequence to which test sequences are compared.
- test and reference sequences are input into a computer, subsequence coordinates are designated if necessary, and sequence algorithm program parameters are designated.
- sequence comparison algorithm then calculates the percent sequence identity for the test sequence(s) relative to the reference sequence, based on the designated program parameters.
- hybridizing specifically to refers to the binding, duplexing, or hybridizing of a molecule only to a particular nucleotide sequence under stringent conditions when that sequence is present in a complex mixture (e.g., total cellular) DNA or RNA.
- Bod(s) substantially refers to complementary hybridization between a probe nucleic acid and a target nucleic acid and embraces minor mismatches that can be accommodated by reducing the stringency ofthe hybridization media to achieve the desired detection ofthe target nucleic acid sequence.
- Stringent hybridization conditions and “stringent hybridization wash conditions” in the context of nucleic acid hybridization experiments such as Southern and Northern hybridization are sequence dependent, and are different under different environmental parameters.
- the T m is the temperature (under defined ionic strength and pH) at which 50% of the target sequence hybridizes to a perfectly matched probe. Specificity is typically the function of post-hybridization washes, the critical factors being the ionic strength and temperature ofthe final wash solution.
- T m can be approximated from the equation of Meinkoth and Wahl, 1984; T m 81.5°C + 16.6 (log M) +0.41 (%GC) - 0.61 (% form) - 500/L; where M is the molarity of monovalent cations, %GC is the percentage of guanosine and cytosine nucleotides in the DNA, % form is the percentage of formamide in the hybridization solution, and L is the length ofthe hybrid in base pairs.
- T m is reduced by about 1°C for each 1% of mismatching; thus, T m , hybridization, and/or wash conditions can be adjusted to hybridize to sequences ofthe desired identity.
- the T m can be decreased 10°C.
- stringent conditions are selected to be about 5°C lower than the thermal melting point I for the specific sequence and its complement at a defined ionic strength and pH.
- severely stringent conditions can utilize a hybridization and/or wash at 1, 2, 3, or 4°C lower than the thermal melting point I;
- moderately stringent conditions can utilize a hybridization and/or wash at 6, 7, 8, 9, or 10°C lower than the thermal melting point I;
- low stringency conditions can utilize a hybridization and/or wash at 11, 12, 13, 14, 15, or 20°C lower than the thermal melting point I.
- hybridization and wash compositions those of ordinary skill will understand that variations in the stringency of hybridization and/or wash solutions are inherently described. If the desired degree of mismatching results in a T of less than 45°C (aqueous solution) or 32°C (formamide solution), it is prefened to increase the SSC concentration so that a higher temperature can be used. An extensive guide to the hybridization of nucleic acids is found in Tijssen, 1993. Generally, highly stringent hybridization and wash conditions are selected to be about 5°C lower than the thermal melting point T m for the specific sequence at a defined ionic strength and pH.
- An example of highly stringent wash conditions is 0.15 M NaCl at 72°C for about 15 minutes.
- An example of stringent wash conditions is a 0.2X SSC wash at 65°C for 15 minutes (see, Sambrook, infra, for a description of SSC buffer).
- a high stringency wash is preceded by a low stringency wash to remove background probe signal.
- An example medium stringency wash for a duplex of, e.g., more than 100 nucleotides is IX SSC at 45°C for 15 minutes.
- An example low stringency wash for a duplex of, e.g., more than 100 nucleotides is 4-6X SSC at 40°C for 15 minutes.
- stringent conditions typically involve salt concentrations of less than about 1.5 M, more preferably about 0.01 to 1.0 M, Na ion concentration (or other salts) at pH 7.0 to 8.3, and the temperature is typically at least about 30°C and at least about 60°C for long robes (e.g., >50 nucleotides).
- Stringent conditions may also be achieved with the addition of destabilizing agents such as formamide.
- a signal to noise ratio of 2X (or higher) than that observed for an unrelated probe in the particular hybridization assay indicates detection of a specific hybridization.
- Nucleic acids that do not hybridize to each other under stringent conditions are still substantially identical if the proteins that they encode are substantially identical. This occurs, e.g., when a copy of a nucleic acid is created using the maximum codon degeneracy permitted by the genetic code.
- Very stringent conditions are selected to be equal to the T m for a particular probe.
- An example of stringent conditions for hybridization of complementary nucleic acids which have more than 100 complementary residues on a filter in a Southern or Northern blot is 50% formamide, e.g., hybridization in 50% formamide, 1 M NaCl, 1%> SDS at 37°C, and a wash in 0. IX SSC at 60 to 65°C.
- Exemplary moderate stringency conditions include hybridization in 40 to 45% formamide, 1.0 M NaCl, 1% SDS at 37°C, and a wash in 0.5X to IX SSC at 55 to 60°C.
- a reference nucleotide sequence preferably hybridizes to the reference nucleotide sequence in 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO 4 , 1 mM EDTA at 50°C with washing in 2X SSC, 0.1% SDS at 50°C, more desirably in 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO 4 , 1 mM EDTA at 50°C with washing in IX SSC, 0.1% SDS at 50°C, more desirably still in 7% sodium dodecyl sulfate (SDS), 0.5 M NaPO 4 , 1 mM EDTA at 50°C with washing in 0.5X SSC, 0.1 % SDS at 50°C, preferably in 7% sodium dode
- DNA shuffling is a method to introduce mutations or reanangements, preferably randomly, in a DNA molecule or to generate exchanges of DNA sequences between two or more DNA molecules, preferably randomly.
- the DNA molecule resulting from DNA shuffling is a shuffled DNA molecule that is a non-naturally occuning DNA molecule derived from at least one template DNA molecule.
- the shuffled DNA preferably encodes a variant polypeptide modified with respect to the polypeptide encoded by the template DNA, and may have an altered biological activity with respect to the polypeptide encoded by the template DNA.
- Recombinant DNA molecule is a combination of DNA sequences that are joined together using recombinant DNA technology and procedures used to join together DNA sequences as described, for example, in Sambrook et al., 1989.
- plant refers to any plant, particularly to seed plant, and "plant cell” is a stractural and physiological unit ofthe plant, which comprises a cell wall but may also refer to a protoplast.
- the plant cell may be in form of an isolated single cell or a cultured cell, or as a part of higher organized unit such as, for example, a plant tissue, or a plant organ.
- “Significant increase” is an increase that is larger than the margin of enor inherent in the measurement technique, preferably an increase by about 2-fold or greater. “Significantly less” means that the decrease is larger than the margin of enor inherent in the measurement technique, preferably a decrease by about 2-fold or greater.
- Virtually any DNA composition may be used for delivery to recipient plant cells, e.g., monocotyledonous cells, to ultimately produce fertile transgenic plants in accordance with the present invention.
- DNA segments in the form of vectors and plasmids, or linear DNA fragments, in some instances containing only the DNA element to be expressed in the plant, and the like, may be employed.
- the construction of vectors which may be employed in conjunction with the present invention will be known to those of skill ofthe art in light ofthe present disclosure (see, e.g., Sambrook et al, 1989; Gelvin et al., 1990).
- Vectors, plasmids, cosmids, YACs (yeast artificial chromosomes), BACs (bacterial artificial chromosomes) and DNA segments for use in fransforming such cells will, of course, generally comprise the cDNA, gene or genes which one desires to introduce into the cells. These DNA constructs can further include structures such as promoters, enhancers, polylinkers, or even regulatory genes as desired.
- the DNA segment or gene chosen for cellular introduction will often encode a protein which will be expressed in the resultant recombinant cells, such as will result in a screenable or selectable trait and/or which will impart an improved phenotype to the regenerated plant. However, this may not always be the case, and the present invention also encompasses transgenic plants inco ⁇ orating non- expressed transgenes.
- Such vectors include, for example, wheat dwarf viras (WDV) "shuttle" vectors, such as pWl-11 and PW1-GUS (Ugaki et al., 1991). These vectors are capable of autonomous replication in maize cells as well as E. coli, and as such may provide increased sensitivity for detecting DNA delivered to transgenic cells.
- WDV wheat dwarf viras
- a replicating vector may also be useful for delivery of genes flanked by DNA sequences from transposable elements such as Ac, Ds, or Mu. It has been proposed (Laufs et al., 1990) that transposition of these elements within the maize genome requires DNA replication.
- transposable elements would be useful for introducing DNA fragments lacking elements necessary for selection and maintenance ofthe plasmid vector in bacteria, e.g., antibiotic resistance genes and origins of DNA replication. It is also proposed that use of a transposable element such as Ac, Ds, or Mu would actively promote integration ofthe desired DNA and hence increase the frequency of stably transformed cells. The use of a transposable element such as Ac, Ds, or Mu may actively promote integration ofthe DNA of interest and hence increase the frequency of stably transformed cells. Transposable elements may be useful to allow separation of genes of mterest from elements necessary for selection and maintenance of a plasmid vector in bacteria or selection of a transformant. By use of a transposable element, desirable and undesirable DNA sequences may be transposed apart from each other in the genome, such that through genetic segregation in progeny, one may identify plants with either the desirable undesirable DNA sequences.
- DNA useful for introduction into plant cells includes that which has been derived or isolated from any source, that may be subsequently characterized as to stracture, size and/or function, chemically altered, and later introduced into plants.
- An example of DNA "derived” from a source would be a DNA sequence that is identified as a useful fragment within a given organism, and which is then chemically synthesized in essentially pure form.
- An example of such DNA "isolated” from a source would be a useful DNA sequence that is excised or removed from said source by chemical means, e.g., by the use of restriction endonucleases, so that it can be further manipulated, e.g., amplified, for use in the invention, by the methodology of genetic engineering.
- Such DNA is commonly refened to as "recombinant DNA.”
- DNA includes completely synthetic DNA, semi-synthetic DNA, DNA isolated from biological sources, and DNA derived from introduced RNA.
- the introduced DNA is not originally resident in the plant genotype which is the recipient ofthe DNA, but it is within the scope ofthe invention to isolate a gene from a given plant genotype, and to subsequently introduce multiple copies ofthe gene into the same genotype, e.g., to enhance production of a given gene product such as a storage protein or a protem that confers tolerance or resistance to water deficit.
- the introduced DNA includes but is not limited to, DNA from plant genes, and non- plant genes such as those from bacteria, yeasts, animals or viruses.
- the introduced DNA can include modified genes, portions of genes, or chimeric genes, including genes from the same or different maize genotype.
- chimeric gene or “chimeric DNA” is defined as a gene or DNA sequence or segment comprising at least two DNA sequences or segments from species which do not combine DNA under natural conditions, or which DNA sequences or segments are positioned or linked in a manner which does not normally occur in the native genome of untransformed plant.
- the introduced DNA used for transformation herein may be circular or linear, double- stranded or single-stranded.
- the DNA is in the form of chimeric DNA, such as plasmid DNA, that can also contain coding regions flanked by regulatory sequences which promote the expression ofthe recombinant DNA present in the resultant plant.
- the DNA may itself compri.se or consist of a promoter that is active in a plant which is derived from a source other than that plant, or may utilize a promoter already present in a plant genotype that is the transformation target.
- the introduced DNA will be relatively small, i.e., less than about 30 kb to niimmize any susceptibility to physical, chemical, or enzymatic degradation which is known to increase as the size ofthe DNA increases.
- the number of proteins, RNA transcripts or mixtures thereof which is introduced into the plant genome is preferably preselected and defined, e.g., from one to about 5-10 such products ofthe introduced DNA may be formed.
- Overexpression can be achieved by insertion of one or more than one extra copy ofthe selected gene. It is, however, not unknown for plants or their progeny, originally transformed with one or more than one extra copy of a nucleotide sequence, to exhibit the effects of underexpression as well as overexpression.
- underexpression there are two principle methods which are commonly refened to in the art as “antisense downregulation” and “sense downregulation” (sense downregulation is also refened to as “cosuppression”). Generically these processes are refened to as "gene silencing". Both of these methods lead to an inhibition of expression ofthe target gene.
- heterologous DNA sequences in a plant host is dependent upon the presence of an operably linked promoter that is functional within the plant host. Choice ofthe promoter sequence will determine when and where within the organism the heterologous DNA sequence is expressed.
- promoters combining elements from more than one promoter may be useful.
- U.S. Patent No. 5,491,288 discloses combining a Cauliflower Mosaic Virus promoter with a histone promoter.
- the elements from the promoters disclosed herein may be combined with elements from other promoters.
- Promoters which are useful for plant transgene expression include those that are inducible, viral, synthetic, constitutive (Odell et al., 1985), temporally regulated, spatially regulated, tissue-specific, and spatio-temporally regulated.
- tissue-specific promoters may be used.
- inducible promoters are the regulatory elements of choice.
- continuous expression is desired throughout the cells of a plant, constitutive promoters are utilized. Additional regulatory sequences upstream and/or downstream from the core promoter sequence may be included in expression constructs of transformation vectors to bring about varying levels of expression of heterologous nucleotide sequences in a transgenic plant.
- promoter will vary depending on the temporal and spatial requirements for expression, and also depending on the target species. In some cases, expression in multiple tissues is desirable. While in others, tissue-specific, e.g., leaf-specific, seed-specific, petal-specific, anther-specific, or pith-specific, expression is desirable. Although many promoters from dicotyledons have been shown to be operational in monocotyledons and vice versa, ideally dicotyledonous promoters are selected for expression in dicotyledons, and monocotyledonous promoters for expression in monocotyledons.
- promoters include, but are not limited to, constitutive, inducible, temporally regulated, developmentally regulated, spatially-regulated, chemically regulated, stress- responsive, tissue-specific, viral and synthetic promoters.
- Promoter sequences are known to be strong or weak. A strong promoter provides for a high level of gene expression, whereas a weak promoter provides for a very low level of gene expression.
- An inducible promoter is a promoter that provides for the turning on and off of gene expression in response to an exogenously added agent, or to an environmental or developmental stimulus.
- a bacterial promoter such as the P tac promoter can be induced to varying levels of gene expression depending on the level of isothiopropylgalactoside added to the transformed bacterial cells.
- An isolated promoter sequence that is a strong promoter for heterologous nucleic acid is advantageous because it provides for a sufficient level of gene expression to allow for easy detection and selection of transformed cells and provides for a high level of gene expression when desired.
- the first of these domains lies immediately upstream ofthe stractural gene and forms the "core promoter region" containing consensus sequences, normally 70 base pairs immediately upstream ofthe gene.
- the core promoter region contains the characteristic CAAT and TATA boxes plus sunounding sequences, and represents a transcription initiation sequence that defines the transcription start point for the stractural gene.
- the presence ofthe core promoter region defines a sequence as being a promoter: if the region is absent, the promoter is non-functional. Furthermore, the core promoter region is insufficient to provide full promoter activity.
- a series of regulatory sequences upstream ofthe core constitute the remainder ofthe promoter.
- the regulatory sequences determine expression level, the spatial and temporal pattern of expression and, for an important subset of promoters, expression under inductive conditions (regulation by external factors such as hght, temperature, chemicals, hormones).
- a range of naturally-occurring promoters are known to be operative in plants and have been used to drive the expression of heterologous (both foreign and endogenous) genes in plants: for example, the constitutive 35S cauliflower mosaic virus (CaMV) promoter, the ripening-enhanced tomato polygalacturonase promoter (Bird et al., 1988), the E8 promoter (Diekman & Fischer, 1988) and the fruit specific 2A1 promoter (Pear et al, 1989) and many others, e.g., U2 and U5 snRNA promoters from maize, the promoter from alcohol dehydrogenase, the Z4 promoter from a gene encoding the Z4 22 kD zein protein, the Z10 promoter from
- nucleotide sequences of this invention can also be expressed under the regulation of promoters that are chemically regulated. This enables the nucleic acid sequence or encoded polypeptide to be synthesized only when the crop plants are treated with the inducing chemicals.
- Chemical induction of gene expression is detailed in EP 0 332 104 (to Ciba-Geigy) and U.S. Patent 5,614,395.
- a prefened promoter for chemical induction is the tobacco PR- la promoter.
- Examples of some constitutive promoters which have been described include the rice actin 1 (Wang et al, 1992; U.S. Patent No. 5,641,876), CaMV 35S (Odell et al., 1985), CaMV 19S (Lawton et al., 1987), nos, Adh, sucrose synthase; and the ubiquitin promoters.
- tissue specific promoters which have been described include the lectin (Vodkin, 1983; Lindstrom et al., 1990) com alcohol dehydrogenase 1 (Vogel et al., 1989; Dennis et al., 1984), com light harvesting complex (Simpson, 1986; Bansal et al., 1992), corn heat shock protein (Odell et al., 1985), pea small subunit RuBP carboxylase (Poulsen et al., 1986), Ti plasmid mannopine synthase (Langridge et al., 1989), Ti plasmid nopaline synthase (Langridge et al., 1989), petunia chalcone isomerase (vanTunen et al., 1988), bean glycine rich protein 1 (Keller et al., 1989), truncated CaMV 35s (Odell et al., 1985), potato patatin (Wenzler et
- Tissue specific enhancers are described in Fromm et al. (1989).
- Inducible promoters that have been described include the ABA- and turgor-inducible promoters, the promoter ofthe auxin-binding protein gene (Schwob et al., 1993), the UDP glucose flavonoid glycosyl-transferase gene promoter (Ralston et al., 1988), the MPI proteinase inhibitor promoter (Cordero et al., 1994), and the gly ceraldehyde-3 -phosphate dehydrogenase gene promoter (Kohler et al., 1995; Quigley et al, 1989; Martinez et al., 1989).
- tissue-specific regulated genes and/or promoters have been reported in plants. These include genes encoding the seed storage proteins (such as napin, cruciferin, beta- conglycinin, and phaseolin) zein or oil body proteins (such as oleosin), or genes involved in fatty acid biosynthesis (including acyl carrier protein, stearoyl-ACP desaturase. And fatty acid desaturases (fad 2-1)), and other genes expressed during embryo development (such as Bce4, see, for example, EP 255378 and Kridl et al., 1991). Particularly useful for seed-specific expression is the pea vicilin promoter (Czako et al., 1992). (See also U.S. Pat. No.
- cDNA clones that are preferentially expressed in cotton fiber have been isolated (John et al., 1992).
- cDNA clones from tomato displaying differential expression during fruit development have been isolated and characterized (Mansson et al., 1985, Slater et al., 1985).
- the promoter for polygalacturonase gene is active in fruit ripening.
- the polygalacturonase gene is described in U.S. Patent No. 4,535,060, U.S. Patent No. 4,769,061, U.S. Patent No. 4,801,590, and U.S. Patent No. 5,107,065, which disclosures are inco ⁇ orated herein by reference.
- tissue-specific promoters include those that direct expression in leaf cells following damage to the leaf (for example, from chewing insects), in tubers (for example, patatin gene promoter), and in fiber cells (an example of a developmentally-regulated fiber cell protein is E6 (John et al., 1992). The E6 gene is most active in fiber, although low levels of transcripts are found in leaf, ovule and flower.
- tissue-specificity of some "tissue-specific" promoters may not be absolute and may be tested by one skilled in the art using the diphtheria toxin sequence.
- tissue-specific expression with "leaky” expression by a combination of different tissue-specific promoters (Beals et al., 1997).
- Other tissue-specific promoters can be isolated by one skilled in the art (see U.S. 5,589,379).
- Several inducible promoters (“gene switches") have been reported. Many are described in the review by Gatz (1996) and Gatz (1997).
- Regulated expression ofthe chimeric transacting viral replication protein can be further regulated by other genetic strategies.
- Cre-mediated gene activation as described by Odell et al. 1990.
- a DNA fragment containing 3 ' regulatory sequence bound by lox sites between the promoter and the replication protein coding sequence that blocks the expression of a chimeric replication gene from the promoter can be removed by C/'e-mediated excision and result in the expression ofthe tr ⁇ ns-acting replication gene.
- the chimeric Cre gene, the chimeric tr ⁇ w ⁇ -acting replication gene, or both can be under the control of tissue- and developmental- specific or inducible promoters.
- An alternate genetic strategy is the use of tRNA suppressor gene.
- the regulated expression of a tRNA suppressor gene can conditionally control expression of a transacting replication protein coding sequence containing an appropriate termination codon as described by Ulmasov et al. 1997.
- a transacting replication protein coding sequence containing an appropriate termination codon as described by Ulmasov et al. 1997.
- either the chimeric tRNA suppressor gene, the chimeric transacting replication gene, or both can be under the control of tissue- and developmental-specific or inducible promoters.
- RNA transcript that interferes with translation ofthe mRNA ofthe native DNA sequence.
- a DNA segment representing the promoter region is removed from the 5' region ofthe gene of interest and operably linked to the coding sequence of a marker (reporter) gene by recombinant DNA techniques well known to the art.
- the reporter gene is operably linked downstream ofthe promoter, so that transcripts initiating at the promoter proceed through the reporter gene.
- Reporter genes generally encode proteins which are easily measured, including, but not limited to, chloramphenicol acetyl transferase (CAT), beta-glucuronidase (GUS), green fluorescent protein (GFP), beta-galactosidase (beta- GAL), and luciferase.
- the construct containing the reporter gene under the control ofthe promoter is then introduced into an appropriate cell type by transfection techniques well known to the art.
- cell lysates are prepared and appropriate assays, which are well known in the art, for the reporter protein are performed.
- CAT were the reporter gene of choice
- the lysates from cells transfected with constructs containing CAT under the control of a promoter under study are mixed with isotopically labeled chloramphenicol and acetyl-coenzyme A (acetyl-CoA).
- the CAT enzyme transfers the acetyl group from acetyl-CoA to the 2- or 3- ⁇ osition of chloramphenicol.
- the reaction is monitored by thin-layer chromatography, which separates acetylated chloramphenicol from unreacted material.
- the reaction products are then visualized by autoradiography.
- the level of enzyme activity conesponds to the amount of enzyme that was made, which in turn reveals the level of expression from the promoter of interest.
- This level of expression can be compared to other promoters to determine the relative strength ofthe promoter under study.
- the level ofthe reporter mRNA can be measured directly, such as by Northern blot analysis.
- mutational and or deletional analyses may be employed to determine the minimal region and/or sequences required to initiate transcription.
- sequences can be deleted at the 5' end ofthe promoter region and/or at the 3' end ofthe promoter region, and nucleotide substitutions introduced. These constracts are then introduced to cells and their activity determined.
- the promoter may be a gamma zein promoter, an oleosin olel ⁇ promoter, a globulinl promoter, an actin I promoter, an actin cl promoter, a sucrose synthetase promoter, an INOPS promoter, an EXM5 promoter, a globulin2 promoter, a b-32, ADPG- pyrophosphorylase promoter, an Ltpl promoter, an Ltp2 promoter, an oleosin olel7 promoter, an oleosin olel8 promoter, an actin 2 promoter, a pollen-specific protein promoter, a pollen- specific pectate lyase promoter, an anther-specific protein promoter (Huffman), an anther- specific gene RTS2 promoter, a pollen- specific gene promoter, a tapeturn-specific gene promoter, tapetum- specific gene RAB24
- the 3N nontranslated regulatory DNA sequence preferably includes from about 50 to about 1,000, more preferably about 100 to about 1,000, nucleotide base pairs and contains plant transcriptional and translational termination sequences.
- Appropriate transcriptional terminators and those which are known to function in plants include the CaMV 35S terminator, the tml terminator, the nopaline synthase terminator, the pea rbcS E9 terminator, the tenninator for the T7 transcript from the octopine synthase gene of Agrobacterium tumefaciens, and the 3N end ofthe protease inhibitor I or II genes from potato or tomato, although other 3N elements known to those of skill in the art can also be employed.
- a gamma coixin, oleosin 3 or other terminator from the genus Coix are examples of the genus Coix.
- Preferred 3' elements include those from the nopaline synthase gene of Agrobacterium tumefaciens (Bevan et al., 1983), the terminator for the T7 transcript from the octopine synthase gene of Agrobacterium tumefaciens, and the 3' end ofthe protease inhibitor I or II genes from potato or tomato.
- the DNA sequence between the transcription initiation site and the start ofthe coding sequence i.e., the untranslated leader sequence, can influence gene expression, one may also wish to employ a particular leader sequence.
- Prefened leader sequences are contemplated to include those which include sequences predicted to direct optimum expression ofthe attached gene, i.e., to include a prefened consensus leader sequence which may increase or maintain mRNA stability and prevent inappropriate initiation of translation.
- sequences will be known to those of skill in the art in light ofthe present disclosure. Sequences that are derived from genes that are highly expressed in plants will be most prefened.
- sequences that have been found to enhance gene expression in transgenic plants include intron sequences (e.g., from Adhl, bronzel, actinl, actin 2 (WO 00/760067), or the sucrose synthase intron) and viral leader sequences (e.g., from TMV, MCMV and AMV).
- viral leader sequences e.g., from TMV, MCMV and AMV.
- TMV Tobacco Mosaic Virus
- MCMV Maize Chlorotic Mottle Virus
- AMV Alfalfa Mosaic Virus
- Picornavirus leaders for example, EMCV leader (Encephalomyocarditis 5 noncoding region) (Elroy-Stein et al., 1989); Potyvirus leaders, for example, TEV leader (Tobacco Etch Virus); MDMV leader (Maize Dwarf Mosaic Virus); Human immunoglobulin heavy-chain binding protein (BiP) leader, (Macejak et al., 1991); Untranslated leader from the coat protein mRNA of alfalfa mosaic virus (AMV RNA 4), (Jobling et al., 1987; Tobacco mosaic viras leader (TMV), (Gallie et al., 1989; and Maize Chlorotic Mottle Virus leader (MCMV) (Lo mel et al., 1991. See also, Della-Cioppa et al., 1987.
- Adh intron 1 (Callis et al., 1987), sucrose synthase intron (Vasil et al., 1989) or TMV omega element (Gallie, et al., 1989), may further be included where desired.
- enhancers include elements from the CaMV 35S promoter, octopine synthase genes (Ellis el al., 1987), the rice actin I gene, the maize alcohol dehydrogenase gene (Callis et al., 1987), the maize shrunken I gene (Vasil et al., 1989), TMV Omega element (Gallie et al., 1989) and promoters from non-plant eukaryotes (e.g. yeast; Ma et al., 1988).
- promoters from non-plant eukaryotes e.g. yeast; Ma et al., 1988.
- Vectors for use in accordance with the present invention may be constracted to include the ocs enhancer element.
- This element was first identified as a 16 bp palindromic enhancer from the octopine synthase (ocs) gene of ultilane (Ellis et al., 1987), and is present in at least 10 other promoters (Bouchez et al., 1989).
- the use of an enhancer element, such as the ocs element and particularly multiple copies ofthe element will act to increase the level of transcription from adjacent promoters when applied in the context of monocot transformation.
- the most desirable DNA segments for introduction into for example a monocot genome may be homologous genes or gene families which encode a desired trait (e.g., increased yield per acre) and which are introduced under the control of novel promoters or enhancers, etc., or perhaps even homologous or tissue specific (e.g., root-, collar/sheath-, whorl-, stalk-, earshank-, kernel- or leaf-specific) promoters or control elements.
- a particular use ofthe present invention will be the targeting of a gene in a constitutive manner or a root-specific manner.
- insect resistant genes may be expressed specifically in the whorl and collar/sheath tissues which are targets for the first and second broods, respectively, of ECB.
- genes encoding proteins with particular activity against rootworm may be targeted directly to root tissues.
- tissue-specific promoters will typically include tissue-specific promoters and may also include other tissue-specific control elements such as enhancer sequences. Promoters which direct specific or enhanced expression in certain plant tissues will be known to those of skill in the art in light ofthe present disclosure. These include, for example, the rbcS promoter, specific for green tissue; the ocs, nos and mas promoters which have higher activity in roots or wounded leaf tissue; a truncated (-90 to +8) 35S promoter which directs enhanced expression in roots, an alpha-tubulin gene that directs expression in roots and promoters derived from zein storage protein genes which direct expression in endosperm.
- ocs octopine synthase
- Tissue specific expression may be functionally accomplished by introducing a constitutively expressed gene (all tissues) in combination with an antisense gene that is expressed only in those tissues where the gene product is not desired.
- a gene coding for the crystal toxin protein from B. thuringiensis (Bt) may be introduced such that it is expressed in all tissues using the 35S promoter from Cauliflower Mosaic Viras. Expression of an antisense transcript ofthe Bt gene in a maize kernel, using for example a zein promoter, would prevent accumulation ofthe Bt protein in seed. Hence the protein encoded by the introduced gene would be present in all tissues except the kernel.
- genes in transgenic plants will be desired only under specified conditions. For example, it is proposed that expression of certain genes that confer resistance to environmental stress factors such as drought will be desired only under actual stress conditions. It is contemplated that expression of such genes throughout a plants development may have detrimental effects. It is known that a large number of genes exist that respond to the environment. For example, expression of some genes such as rbcS, encoding the small subunit of ribulose bisphosphate carboxylase, is regulated by light as mediated through phytochrome. Other genes are induced by secondary stimuli. For example, synthesis of abscisic acid (ABA) is induced by certain environmental factors, including but not limited to water stress.
- ABA abscisic acid
- genes confening resistance to insect predation would be desired only under conditions of actual insect infestation. Therefore, for some desired traits inducible expression of genes in transgenic plants will be desired.
- vectors may be constructed and employed in the intracellular targeting of a specific gene product within the cells of a transgenic plant or in directing a protein to the extracellular environment. This will generally be achieved by joining a DNA sequence encoding a transit or signal peptide sequence to the coding sequence of a particular gene. The resultant transit, or signal, peptide will transport the protein to a particular intracellular, or extracellular destination, respectively, and will then be post-translationally removed.
- Transit or signal peptides act by facilitating the transport of proteins through intracellular membranes, e.g., vacuole, vesicle, plastid and mitochondrial membranes, whereas signal peptides direct proteins through the extracellular membrane.
- a particular example of such a use concerns the direction of a herbicide resistance gene, such as the EPSPS gene, to a particular organelle such as the chloroplast rather than to the cytoplasm. This is exemplified by the use ofthe rbcs transit peptide which confers plastid- specific targeting of proteins.
- these sequences may increase the accumulation of gene product protecting them from proteolytic degradation.
- These sequences also allow for additional mRNA sequences from highly expressed genes to be attached to the coding sequence ofthe genes. Since mRNA being translated by ribosomes is more stable than naked mRNA, the presence of translatable mRNA in front ofthe gene may increase the overall stability ofthe mRNA transcript from the gene and thereby increase synthesis ofthe gene product. Since transit and signal sequences are usually post- translationally removed from the initial translation product, the use of these sequences allows for the addition of extra translated sequences that may not appear on the final polypeptide. Targeting of certain proteins may be desirable in order to enhance the stability of the protein (U.S. Patent No. 5,545,818).
- DNA itself within a cell.
- Within the nucleus itself it would be useful to target a gene in order to achieve site specific integration.
- Other elements include those that can be regulated by endogenous or exogenous agents, e.g., by zinc finger proteins, including naturally occurring zinc finger proteins or chimeric zinc finger proteins (see, e.g., U.S. Patent No.
- a chimeric zinc finger protein may include amino acid sequences which bind to a specific DNA sequence (the zinc finger) and amino acid sequences that activate (e.g., GAL 4 sequences) or repress the transcription ofthe sequences linked to the specific DNA sequence.
- the invention relates to an isolated plant, e.g., Arabidopsis, Chenopodium and rice, nucleic acid molecule comprising a gene having an open reading frame, the expression of which is altered in response to pathogen infection, as well as the endogenous plant promoters for those genes.
- the expression of these genes may also be altered in response to non-pathogens, e.g., in response to environmental devismuli.
- the nucleic acid molecules can be used in pathogen control strategies, e.g., by overexpressing nucleic acid molecules which can confer tolerance to a cell, or by altering the expression of host genes which are required for pathogen infection, e.g., by "knocking out” the expression of at least one genomic copy ofthe gene.
- Plants having genetic disruptions in host genes may be less susceptible to infection, e.g., due to a decrease or absence of a host protein needed for infection, or, alternatively, hypersusceptible to infection. Plants that are hypersusceptible to infection may be useful to prepare transgenic plants as the expression ofthe gene(s) which was disrupted may be related to gene silencing.
- Preferred sources from which the nucleic acid molecules ofthe invention can be obtained or isolated include, but are not limited to, corn (Zea mays), Brassica sp. (e.g., B. napus, B. rapa, B. juncea), particularly those Brassica species useful as sources of seed oil, alfalfa (Medicago sativa), rice (Oryza sativa), rye (Secale cereale), sorghum (Sorghum bicolor, Sorghum vulgare), millet (e.g., pearl millet (Pennisetum glaucum), proso millet (Panicum miliaceum), foxtail millet (Setaria italica), finger millet (Eleusine coracana)), sunflower (Helianthus annuus), safflower (Carthamus tinctorius), wheat (Triticum aestivum), soybean (Glycine max), tobacco (Nicotiana tabacum), potato (Solanum tuberos
- Duckweed (Lemna, see WO 00/07210) includes members ofthe family Lemnaceae. There are known four genera and 34 species of duckweed as follows: genus Lemna (L. aequinoctialis, L. disperma, L. ecuadoriensis, L. gibba, L. japonica, L. minor, L. miniscula, L. obscura, L. perpusilla, L. tenera, L. trisulca, L. turionifera, L. valdiviana); genus Spirodela (S. intermedia, S. polyrrhiza, S. punctata); genus Woffia (Wa. Angusta, Wa. Arrhiza, Wa.
- genus Lemna L. aequinoctialis, L. disperma, L. ecuadoriensis, L. gibba, L. japonica, L. minor, L. miniscula, L.
- Lemna gibba, Lemna minor, and Lemna miniscula axe prefened, with Lemn ⁇ minor and Lemn ⁇ miniscula being most prefened.
- Lemna species can be classified using the taxonomic scheme described by Landolt, Biosystematic Investigation on the Family of Duckweeds: The family of Lemnaceae - A Monograph Study. Geobatanischen Institut ETH, Stainless Rubel, Zurich (1986)).
- Vegetables from which to obtain or isolate the nucleic acid molecules ofthe invention include, but are not limited to, tomatoes (Lycopersicon esculentum), lettuce (e.g., Lactuca sativa), green beans (Phaseolus vulgaris), lima beans (Phaseolus limensis), peas (Lathyrus spp.), and members ofthe genus Cucumis such as cucumber (C. sativus), cantaloupe (C. cantalupensis), and musk melon (C melo).
- tomatoes Locopersicon esculentum
- lettuce e.g., Lactuca sativa
- green beans Phaseolus vulgaris
- lima beans Phaseolus limensis
- peas Lathyrus spp.
- members ofthe genus Cucumis such as cucumber (C. sativus), cantaloupe (C. cantalupensis), and musk melon (C melo).
- Ornamentals from which to obtain or isolate the nucleic acid molecules ofthe invention include, but are not limited to, azalea (Rhododendron spp.), hydrangea (Macrophylla hydrangea), hibiscus (Hibiscus rosasanensis), roses (Rosa spp.), tulips (Tulipa spp.), daffodils (Narcissus spp.), petunias (Petunia hybrida), carnation (Dianthus caryophyllus), poinsettia (Euphorbia pulcherrima), and chrysanthemum.
- Conifers that may be employed in practicing the present invention include, for example, pines such as loblolly pine (Pinus taeda), slash pine (Pinus elliotii), ponderosa pine (Pinus ponderosa), lodgepole pine (Pinus contorta), and Monterey pine (Pinus radiata), Douglas-fir (Pseudotsuga menziesii); Western hemlock (Tsuga ultilane); Sitka spruce (Picea glauca); redwood (Sequoia sempervirens); trae firs such as silver fir (Abies amabilis) and balsam fir (Abies balsamea); and cedars such as Western red cedar (Thuja plicata) and Alaska yellow-cedar (Chamaecyparis nootkatensis).
- pines such as loblolly pine (Pinus taeda), slash pine
- Leguminous plants from which the nucleic acid molecules of the invention can be isolated or obtained include, but are not limited to, beans and peas.
- Beans include guar, locust bean, fenugreek, soybean, garden beans, cowpea, mungbean, lima bean, fava bean, lentils, chickpea, and the like.
- Legumes include, but are not limited to, Arachis, e.g., peanuts, Vicia, e.g., crown vetch, hairy vetch, adzuki bean, mung bean, and chickpea, Lupinus, e.g., lupine, trifolium, Phaseolus, e.g., common bean and lima bean, Pisum, e.g., field bean, Melilotus, e.g., clover, Medicago, e.g., alfalfa, Lotus, e.g., trefoil, lens, e.g., lentil, and false indigo.
- Arachis e.g., peanuts
- Vicia e.g., crown vetch, hairy vetch, adzuki bean, mung bean, and chickpea
- Lupinus e.g., lupine, trifolium
- Phaseolus e.g., common bean and lim
- nucleic acid molecules ofthe invention include Acacia, aneth, artichoke, arugula, blackberry, canola, cilantro, Clementines, escarole, eucalyptus, fennel, grapefruit, honey dew, jicama, kiwifruit, lemon, lime, mushroom, nut, okra, orange, parsley, persimmon, plantain, pomegranate, poplar, radiata pine, radicchio, Southern pine, sweetgum, tangerine, triticale, vine, yams, apple, pear, quince, cherry, apricot, melon, hemp, buckwheat, grape, raspberry, chenopodium, blueberry, nectarine, peach, plum, strawberry, watermelon, eggplant, pepper, cauliflower, Brassica, e.g., broccoli, cabbage, ultilan sprouts, onion, carrot, leek, beet, broad bean,
- nucleic acid molecules are ornamental plants including, but not limited to, impatiens, Begonia, Pelargonium, Viola, Cyclamen, Verbena, Vinca, Tagetes, Primula, Saint Paulia, Agertum, Amaranthus, Antihinhinum, Aquilegia, Cineraria, Clover, Cosmo, Cowpea, Dahlia, Datura, Delphinium, Gerbera, Gladiolus, Gloxinia, Hippeastrum, Mesembryanthemum, Salpiglossos, and Zinnia, and plants such as those shown in Table 1.
- Prefened forage and turfgrass nucleic acid sources for the nucleic acid molecules of the invention include, but are not limited to, alfalfa, orchard grass, tall fescue, perennial ryegrass, creeping bent grass, and redtop.
- prefened sources include, but are not limited to, crop plants and in particular cereals (for example, corn, alfalfa, sunflower, rice, Brassica, canola, soybean, barley, soybean, sugarbeet, cotton, safflower, peanut, sorghum, oat, rye, rape, wheat, millet, tobacco, and the like), and even more preferably corn, rice and soybean.
- the present invention is directed to a nucleic acid molecule comprising a nucleotide sequence isolated or obtained from any plant which encodes a polypeptide having at least 70% amino acid sequence identity to a polypeptide encoded by a gene comprising any one of SEQ ID NOs:l-953, 1954-1966, 2000-2129 or 2662-4737, or a gene comprising SEQ ID NOs:2137-2661 or 4738-6813.
- orthologs may be identified or isolated from the genome of any desired organism, preferably from another plant, according to well known techniques based on their sequence similarity to the Arabidopsis, Chenopodium and rice nucleic acid sequences, e.g., hybridization, PCR or computer generated sequence comparisons. For example, all or a portion of a particular Arabidopsis, Chenopodium and rice nucleic acid sequence is used as a probe that selectively hybridizes to other gene sequences present in a population of cloned genomic DNA fragments or cDNA fragments (i.e., genomic or cDNA libraries) from a chosen source organism.
- genomic and cDNA libraries may be prepared from any cell or tissue of an organism.
- Such techniques include hybridization screening of plated DNA libraries (either plaques or colonies; see, e.g., Sambrook et al., 1989) and amplification by PCR using oligonucleotide primers preferably conesponding to sequence domains conserved among related polypeptide or subsequences ofthe nucleotide sequences provided herein (see, e.g., Innis et al., 1990). These methods are particularly well suited to the isolation of gene sequences from organisms closely related to the organism from which the probe sequence is derived.
- oligonucleotide primers can be designed for use in PCR reactions to amplify conesponding DNA sequences from cDNA or genomic DNA extracted from any plant of interest. Methods for designing PCR primers and PCR cloning are generally known in the art.
- hybridization techniques all or part of a known nucleotide sequence is used as a probe that selectively hybridizes to other conesponding nucleotide sequences present in a population of cloned genomic DNA fragments or cDNA fragments (i.e., genomic or cDNA libraries) from a chosen organism.
- the hybridization probes may be genomic DNA fragments, cDNA fragments, RNA fragments, or other oligonucleotides, and may be labeled with a detectable group such as 32 P, or any other detectable marker.
- probes for hybridization can be made by labeling synthetic oligonucleotides based on the sequence ofthe invention.
- sequences that hybridize to the sequences disclosed herein will have at least 40% to 50%, about 60% to 70% and even about 80% 85%, 90%, 95% to 98% or more identity with the disclosed sequences. That is, the sequence similarity of sequences may range, sharing at least about 40% to 50%, about 60% to 70%, and even about 80%, 85%, 90%, 95% to 98% sequence similarity.
- nucleic acid molecules ofthe invention can also be identified by, for example, a search of known databases for genes encoding polypeptides having a specified amino acid sequence identity or DNA having a specified nucleotide sequence identity. Methods of alignment of sequences for comparison are well known in the art and are described hereinabove.
- the means for mutagenizing a DNA segment ofthe cunent invention are well-known to those of skill in the art. As indicated, modifications may be made by random or site-specific mutagenesis procedures.
- the DNA may be modified by altering its stracture through the addition or deletion of one or more nucleotides from the sequence which encodes the conesponding un-modified sequences.
- Mutagenesis may be performed in accordance with any ofthe techniques known in the art, such as, and not limited to, synthesizing an oligonucleotide having one or more mutations within the sequence of a particular regulatory region.
- site-specific mutagenesis is a technique useful in the preparation of promoter mutants, through specific mutagenesis ofthe underlying DNA.
- the technique further provides a ready ability to prepare and test sequence variants, for example, inco ⁇ orating one or more ofthe foregoing considerations, by introducing one or more nucleotide sequence changes into the DNA.
- Site-specific mutagenesis allows the production of mutants through the use of specific oligonucleotide sequences which encode the DNA sequence ofthe desired mutation, as well as a sufficient number of adjacent nucleotides, to provide a primer sequence of sufficient size and sequence complexity to form a stable duplex on both sides ofthe deletion junction being traversed.
- a primer of about 17 to about 75 nucleotides or more in length is prefened, with about 10 to about 25 or more residues on both sides of the junction ofthe sequence being altered.
- the technique of site-specific mutagenesis is well known in the art, as exemplified by various publications.
- the technique typically employs a phage vector which exists in both a single stranded and double stranded form.
- Typical vectors useful in site-directed mutagenesis include vectors such as the Ml 3 phage. These phage are readily commercially available and their use is generally well known to those skilled in the art.
- Double stranded plasmids also are routinely employed in site directed mutagenesis which eliminates the step of transfening the gene of interest from a plasmid to a phage.
- site-directed mutagenesis in accordance herewith is performed by first obtaining a single-stranded vector or melting apart of two strands of a double stranded vector which includes within its sequence a DNA sequence which encodes the promoter.
- An oligonucleotide primer bearing the desired mutated sequence is prepared, generally synthetically. This primer is then annealed with the single-stranded vector, and subjected to DNA polymerizing enzymes such as E. coli polymerase I Klenow fragment, in order to complete the synthesis ofthe mutation-bearing strand.
- DNA polymerizing enzymes such as E. coli polymerase I Klenow fragment
- This heteroduplex vector is then used to transfonn or transfect appropriate cells, such as E. coli cells, and cells are selected which include recombinant vectors bearing the mutated sequence anangement.
- Vector DNA can then be isolated from these cells and used for plant transformation.
- a genetic selection scheme was devised by Kunkel et al. (1987) to enrich for clones incorporating mutagenic oligonucleotides.
- the use of PCR with commercially available thermostable enzymes such as Taq polymerase may be used to incorporate a mutagenic oligonucleotide primer into an amplified DNA fragment that can then be cloned into an appropriate cloning or expression vector.
- PCR-mediated mutagenesis procedures of Tomic et al. (1990) and Upender et al. (1995) provide two examples of such protocols.
- a PCR employing a thennostable ligase in addition to a thermostable polymerase also may be used to incorporate a phosphorylated mutagenic oligonucleotide into an amplified DNA fragment that may then be cloned into an appropriate cloning or expression vector.
- the mutagenesis procedure described by Michael (1994) provides an example of one such protocol.
- sequence variants of DNA segments using site-directed mutagenesis is provided as a means of producing potentially useful species and is not meant to be limiting as there are other ways in which sequence variants of DNA sequences may be obtained.
- recombinant vectors encoding the desired promoter sequence may be treated with mutagenic agents, such as hydroxylamine, to obtain sequence variants.
- an unmodified or modified nucleotide sequence of the present invention can be varied by shuffling the sequence ofthe invention.
- the sequence of interest is operably linked to a selectable or screenable marker gene and expression of the marker gene is tested in transient expression assays with protoplasts or in stably transformed plants. It is known to the skilled artisan that DNA sequences capable of driving expression of an associated nucleotide sequence are build in a modular way. Accordingly, expression levels from shorter DNA fragments may be different than the one from the longest fragment and may be different from_each other.
- deletion of a down-regulating upstream element will lead to an increase in the expression levels of the associated nucleotide sequence while deletion of an up-regulating element will decrease the expression levels of the associated nucleotide sequence. It is also known to the skilled artisan that deletion of development-specific or a tissue-specific element will lead to a temporally or spatially altered expression profile of the associated nucleotide sequence.
- oligonucleotide directed mutagenesis procedure refers to template-dependent processes and vector-mediated propagation which result in an increase in the concentration of a specific nucleic acid molecule relative to its initial concentration, or in an increase in the concentration of a detectable signal, such as amplification.
- oligonucleotide directed mutagenesis procedure also is intended to refer to a process that involves the template-dependent extension of a primer molecule.
- template- dependent process refers to nucleic acid synthesis of an RNA or a DNA molecule wherein the sequence ofthe newly synthesized strand of nucleic acid is dictated by the well- known rules of complementary base pairing (see, for example, Watson and Rarnstad, 1987).
- vector mediated methodologies involve the introduction ofthe nucleic acid fragment into a DNA or RNA vector, the clonal amplification ofthe vector, and the recovery ofthe amplified nucleic acid fragment. Examples of such methodologies are provided by U.S. Patent No. 4,237,224.
- a number of template dependent processes are available to amplify the target sequences of interest present in a sample, such methods being well known in the art and specifically disclosed herein below.
- a clone comprising a promoter has been isolated in accordance with the instant invention, one may wish to delimit the essential promoter regions within the clone.
- One efficient, targeted means for preparing mutagenizing promoters relies upon the identification of putative regulatory elements within the promoter sequence. This can be initiated by comparison with promoter sequences known to be expressed in similar tissue-specific or developmentally unique manner. Sequences which are shared among promoters with similar expression patterns are likely candidates for the binding of transcription factors and are thus likely elements which confer expression patterns. Confirmation of these putative regulatory elements can be achieved by deletion analysis of each putative regulatory region followed by functional analysis of each deletion constract by assay of a reporter gene which is functionally attached to each constract. As such, once a starting promoter sequence is provided, any of a number of different deletion mutants ofthe starting promoter could be readily prepared.
- deletion mutants, deletion mutants ofthe promoter ofthe invention also could be randomly prepared and then assayed. With this strategy, a series of constructs are prepared, each containing a different portion ofthe clone (a subclone), and these constructs are then screened for activity.
- a suitable means for screening for activity is to attach a deleted promoter or intron construct which contains a deleted segment to a selectable or screenable marker, and to isolate only those cells expressing the marker gene. In this way, a number of different, deleted promoter constructs are identified which still retain the desired, or even enhanced, activity. The smallest segment which is required for activity is thereby identified through comparison ofthe selected constructs. This segment may then be used for the construction of vectors for the expression of exogenous genes.
- B. Marker Genes In order to improve the ability to identify transformants, one may desire to employ a selectable or screenable marker gene as, or in addition to, the expressible gene of interest.
- Marker genes are genes that impart a distinct phenotype to cells expressing the marker gene and thus allow such transformed cells to be distinguished from cells that do not have the marker. Such genes may encode either a selectable or screenable marker, depending on whether the marker confers a trait which one can "select” for by chemical means, i.e., through the use of a selective agent (e.g., a herbicide, antibiotic, or the like), or whether it is simply a trait that one can identify through observation or testing, i.e., by 'screening' (e.g., the R-locus trait, the green fluorescent protein (GFP)).
- a selective agent e.g., a herbicide, antibiotic, or the like
- GFP green fluorescent protein
- selectable or screenable marker genes are also genes which encode a "secretable marker” whose secretion can be detected as a means of identifying or selecting for transformed cells. Examples include markers which encode a secretable antigen that can be identified by antibody interaction, or even secretable enzymes which can be detected by their catalytic activity.
- Secretable proteins fall into a number of classes, including small, diffusible proteins detectable, e.g., by ELISA; small active enzymes detectable in extracellular solution (e.g., alpha-amylase, beta-lactamase, phosphinothricin acetyltransferase); and proteins that are inserted or trapped in the cell wall (e.g., proteins that include a leader sequence such as that found in the expression unit of extensin or tobacco PR-S).
- selectable secretable markers the use of a gene that encodes a protein that becomes sequestered in the cell wall, and which protein includes a unique epitope is considered to be particularly advantageous.
- Such a secreted antigen marker would ideally employ an epitope sequence that would provide low background in plant tissue, a promoter- leader sequence that would impart efficient expression and targeting across the plasma membrane, and would produce protein that is bound in the cell wall and yet accessible to antibodies.
- a normally secreted wall protein modified to include a unique epitope would satisfy all such requirements.
- HPRG hydroxyproline rich glycoprotein
- the maize HPRG (Steifel et al., 1990) molecule is well characterized in terms of molecular biology, expression and protein structure.
- any one of a variety of ultilane and/or glycine-rich wall proteins could be modified by the addition of an antigenic site to create a screenable marker.
- a secretable screenable marker concerns the use of a maize sequence encoding the wall protein HPRG, modified to include a 15 residue epitope from the pro-region of murine interleukin, however, virtually any detectable epitope may be employed in such embodiments, as selected from the extremely wide variety of antigen- antibody combinations known to those of skill in the art.
- the unique extracellular epitope can then be straightforwardly detected using antibody labeling in conjunction with chromogenic or fluorescent adjuncts.
- selectable markers for use in connection with the present invention include, but are not limited to, a neo gene which codes for kanamycin resistance and can be selected for using kanamycin, G418, paromomycin, and the like; a bar gene which codes for bialaphos or phosphinothricin resistance; a gene which encodes an altered EPSP synthase protein (Hinchee et al., 1988) thus confening glyphosate resistance; a nitrilase gene such as bxn from Klebsiella ozaenae which confers resistance to bromoxynil (Stalker et al., 1988); a mutant acetolactate synthase gene (ALS) which confers resistance to imidazolinone, sulfonylurea or other ALS- inhibiting chemicals (European Patent Application 154,204, 1985); a methotrexate-resistant DHFR gene (ThiUet et al.,
- Prefened selectable marker genes encode phosphinothricin acetyltransferase; glyphosate resistant EPSPS, aminoglycoside phosphotransferase; hygromycin phosphotransferase, or neomycin phosphotransferase. Where a mutant EPSP synthase gene is employed, additional benefit may be realized through the incorporation of a suitable chloroplast transit peptide, CTP (European Patent Application 0,218,571, 1987).
- a selectable marker gene capable of being used in systems to select transformants is the genes that encode the enzyme phosphinothricin acetyltransferase, such as the bar gene from Streptomyces hygroscopicus or the pat gene from Streptomyces viridochromogenes.
- the enzyme phosphinothricin acetyl transferase (PAT) inactivates the active ingredient in the herbicide bialaphos, phosphinothricin (PPT). PPT inhibits glutamine synthetase, (Murakami et al., 1986; Twell et al., 1989) causing rapid accumulation of ammonia and cell death.
- PPT phosphinothricin
- a particularly useful gene for this purpose is the bar ox pat genes obtainable from species of Streptomyces (e.g., ATCC No. 21,705).
- the cloning ofthe bar gene has been described (Murakami et al., 1986; Thompson et al., 1987) as has the use ofthe bar gene in the context of plants other than monocots (De Block et al., 1987; De Block et al.,_1989).
- Selection markers resulting in positive selection such as a phosphomannose isomerase gene, as described in patent application WO 93/05163, may also be used.
- Alternative genes to be used for positive selection are described in WO 94/20627 and encode xyloisomerases and phosphomanno-isomerases such as mannose-6-phosphate isomerase and mannose- 1 -phosphate isomerase; phosphomanno mutase; mannose epimerases such as those which convert carbohydrates to mannose or mannose to carbohydrates such as glucose or galactose; phosphatases such as mannose or xylose phosphatase, mannose-6-phos ⁇ hatase and mannose- 1 -phosphatase, and permeases which are involved in the transport of mannose, or a derivative, or a precursor thereof into the cell.
- Transformed cells are identified without damaging or killing the non-transformed cells in the population and without co-introduction of antibiotic or herbicide resistance genes. As described in WO 93/05163, in addition to the fact that the need for antibiotic or herbicide resistance genes is eliminated, it has been shown that the positive selection method is often far more efficient than traditional negative selection. 2. Screenable Markers
- Screenable markers that may be employed include, but are not limited to, a beta- glucuronidase (GUS) or uidA gene which encodes an enzyme for which various chromogenic substrates are known; an R-locus gene, which encodes a product that regulates the production of anthocyanin pigments (red color) in plant tissues (Dellaporta et al., 1988); a beta-lactamase gene (Sutcliffe, 1978), which encodes an enzyme for which various chromogenic substrates are known (e.g., PAD AC, a chromogenic cephalosporin); axylE gene (Zukowsky et al., 1983) which encodes a catechol dioxygenase that can convert chromogenic catechols; an V-amylase gene (Ikuta et al., 1990); a tyrosinase gene (Katz et al., 1983) which encodes an enzyme capable of oxidizing t
- Genes from the maize R gene complex are contemplated to be particularly useful as screenable markers.
- the R gene complex in maize encodes a protein that acts to regulate the production of anthocyanin pigments in most seed and plant tissue.
- a gene from the R gene complex was applied to maize transformation, because the expression of this gene in transformed cells does not harm the cells. Thus, an R gene introduced into such cells will cause the expression of a red pigment and, if stably incorporated, can be visually scored as a red sector.
- a maize line is canies dominant ultila for genes encoding the enzymatic intemiediates in the anthocyanin biosynthetic pathway (C2, Al, A2, Bzl and Bz2) (Roth et al., 1990), but carries a recessive allele at the R locus, transformation of any cell from that line with R will result in red pigment formation.
- Exemplary lines include Wisconsin 22 which contains the rg-Stadler allele and TRI 12, a K55 derivative which is r-g, b, PI.
- any genotype of maize can be utilized if the Cl and R alleles are introduced together.
- R gene regulatory regions may be employed in chimeric constructs in order to provide mechanisms for controlling the expression of chimeric genes. More diversity of phenotypic expression is known at the R locus than at any other locus (Coe et al., 1988). It is contemplated that regulatory regions obtained from regions 5' to the stractural R gene would be valuable in directing the expression of genes, e.g., insect resistance, drought resistance, herbicide tolerance or other protein coding regions. For the purposes ofthe present invention, it is believed that any ofthe various R gene family members may be successfully employed (e.g., P, S, Lc, etc.). However, the most preferred will generally be Sn (particularly Sn:bol3). Sn is a dominant member ofthe R gene complex and is functionally similar to the R and B loci in that Sn controls the tissue specific deposition of anthocyanin pigments in certain seedling and plant cells, therefore, its phenotype is similar to R.
- a further screenable marker contemplated for use in the present invention is firefly luciferase, encoded by the lux gene.
- the presence ofthe lux gene in transformed cells may be detected using, for example, X-ray film, scintillation counting, fluorescent spectrophotometry, low-light video cameras, photon counting cameras or multiwell luminometry. It is also envisioned that this system may be developed for populational screening for bioluminescence, such as on tissue culture plates, or even for whole plant screening. Where use of a screenable marker gene such as lux or GFP is desired, benefit may be realized by creating a gene fusion between the screenable marker gene and a selectable marker gene, for example, a GFP-NPTII gene fusion. This could allow, for example, selection of transformed cells followed by screening of transgenic plants or seeds.
- genes of interest are reflective ofthe commercial markets and interests of those involved in the development ofthe crop. Crops and markets of interest changes, and as developing nations open up world markets, new crops and technologies will also emerge. In addition, as the understanding of agronomic traits and characteristics such as yield and heterosis increase, the choice of genes for transformation will change accordingly.
- General categories of genes of interest include, for example, those genes involved in information, such as zinc fingers, those involved in communication, such as kinases, and those involved in housekeeping, such as heat shock proteins.
- transgenes include genes encoding important traits for agronomics, insect resistance, disease resistance, herbicide resistance, sterility, grain characteristics, and commercial products. Genes of interest include, generally, those involved in starch, oil, carbohydrate, or nutrient metabolism, as well as those affecting kernel size, sucrose loading, zinc finger proteins, see, e.g., US. Patent No. 5,789,538, WO 99/48909; WO 99/45132; WO 98/53060; WO 98/53057; WO 98/53058; WO 00/23464; WO 95/19431; and WO 98/54311, and the like.
- transgene expression level and regulation of a transgene in a plant can vary significantly from line to line. Thus, one has to test several lines to find one with the desired expression level and regulation. Once a line is identified with the desired regulation specificity of a chimeric Cre transgene, it can be crossed with lines carrying different inactive replicons or inactive transgene for activation.
- sequences which may be linked to the gene of interest which encodes a polypeptide are those which can target to a specific organelle, e.g., to the lnitochondria, nucleus, or plastid, within the plant cell.
- Targeting can be achieved by providing the polypeptide with an appropriate targeting peptide sequence, such as a secretory signal peptide (for secretion or cell wall or membrane targeting, a plastid transit peptide, a chloroplast transit peptide, e.g., the chlorophyll ab binding protein, a mitochondrial target peptide, a vacuole targeting peptide, or a nuclear targeting peptide, and the like.
- a secretory signal peptide for secretion or cell wall or membrane targeting
- a plastid transit peptide for secretion or cell wall or membrane targeting
- chloroplast transit peptide e.g., the chlorophyll ab binding protein
- mitochondrial target peptide
- the small subunit of ribulose bisphosphate carboxylase transit peptide, the EPSPS transit peptide or the dihydrodipicolinic acid synthase transit peptide may be used.
- plastid organelle targeting sequences see WO 00/12732.
- Plastids are a class of plant organelles derived from proplastids and include chloroplasts, leucoplasts, aravloplasts, and chromoplasts.
- the plastids are major sites of biosynthesis in plants. In addition to photosynthesis in the chloroplast, plastids are also sites of lipid biosynthesis, nitrate reduction to ammonium, and starch storage.
- Transgenes used with the present invention will often be genes that direct the expression of a particular protein or polypeptide product, but they may also be non-expressible DNA segments, e.g., transposons such as Ds that do no direct their own transposition.
- an "expressible gene” is any gene that is capable of being transcribed into RNA (e.g., mRNA, antisense RNA, etc.) or translated into a protein, expressed as a trait of interest, or the like, etc., and is not limited to selectable, screenable or non-selectable marker genes.
- the invention also contemplates that, where both an expressible gene that is not necessarily a marker gene is employed in combination with a marker gene, one may employ the separate genes on either the same or different DNA segments for transformation. In the latter case, the different vectors are delivered concurrently to recipient cells to maximize cotransformation. The choice ofthe particular DNA segments to be delivered to the recipient cells will often depend on the purpose ofthe transformation.
- One ofthe major purposes of transformation of crop plants is to add some commercially desirable, agronomically important traits to the plant.
- Such traits include, but are not limited to, herbicide resistance or tolerance; insect resistance or tolerance; disease resistance or tolerance (viral, bacterial, fungal, nematode); stress tolerance and/or resistance, as exemplified by resistance or tolerance to drought, heat, chilling, freezing, excessive moisture, salt stress; oxidative stress; increased yields; food content and makeup; physical appearance; male sterility; drydown; standability; prolificacy; starch properties; oil quantity and quality; and the like.
- the present invention contemplates the transformation of a recipient cell with more than one advantageous transgene.
- Two or more transgenes can be supplied in a single transformation event using either distinct transgene-encoding vectors, or using a single vector incorporating two or more gene coding sequences.
- plasmids bearing the bar and aroA expression units in either convergent, divergent, or colinear orientation are considered to be particularly useful.
- Further prefened combinations are those of an insect resistance gene, such as a Bt gene, along with a protease inhibitor gene such as pinll, or the use of bar in combination with either ofthe above genes.
- any two or more transgenes of any description such as those conferring herbicide, insect, disease (viral, bacterial, fungal, nematode) or drought resistance, male sterility, drydown, standability, prolificacy, starch properties, oil quantity and quality, or those increasing yield or nutritional quality may be employed as desired.
- the bar and pat genes code for an enzyme, phosphinothricin acetyltransferase (PAT), which inactivates the herbicide phosphinothricin and prevents this compound from inhibiting glutamine synthetase enzymes.
- PAT phosphinothricin acetyltransferase
- the enzyme 5- enolpyravylshikimate 3-phosphate synthase (EPSP Synthase) is normally inhibited by the herbicide N-(phosphonomethyl)glycine (glyphosate).
- genes are known that encode glyphosate-resistant EPSP Synthase enzymes. These genes are particularly contemplated for use in monocot transformation.
- the deh gene encodes the enzyme dalapon dehalogenase and confers resistance to the herbicide dalapon.
- the bxn gene codes for a specific nitrilase enzyme that converts bromoxynil to a non-herbicidal degradation product.
- An important aspect ofthe present invention concerns the introduction of insect resistance-conferring genes into plants.
- Potential insect resistance genes which can be introduced include Bacillus thuringiensis crystal toxin genes or Bt genes (Watrud et al., 1985). Bt genes may provide resistance to lepidopteran or coleopteran pests such as European Corn Borer (ECB) and corn rootworm (CRW).
- ECB European Corn Borer
- CRW corn rootworm
- Prefened Bt toxin genes for use in such embodhnents include the CryIA(b) and Cry ⁇ A(c) genes. Endotoxin genes from other species of P. thuringiensis which affect insect growth or development may also be employed in this regard.
- Bt toxin genes The poor expression of Pt toxin genes in plants is a well-documented phenomenon, and the use of different promoters, fusion proteins, and leader sequences has not led to significant increases in Bt protein expression (Vaeck et al., 1989; Barton et al., 1987). It is therefore contemplated that the most advantageous Bt genes for use in the transformation protocols disclosed herein will be those in which the coding sequence has been modified to effect increased expression in plants, and more particularly, those in which maize prefened codons have been used. Examples of such modified Bt toxin genes include the variant Bt CryIA(b) gene tenned lab ⁇ (Perlak et al., 1991) and the synthetic Cry ⁇ A(c) genes termed 1800a and 1800b.
- Protease inhibitors may also provide insect resistance (Johnson et al., 1989), and will thus have utility in plant transformation.
- the use of a protease inhibitor II gene, pinll, from tomato or potato is envisioned to be particularly useful. Even more advantageous is the use of a pinll gene in combination with a Bt toxin gene, the combined effect of which has been discovered by the present inventors to produce synergistic insecticidal activity.
- Other genes which encode inhibitors ofthe insects' digestive system, or those that encode enzymes or co- factors that facilitate the production of inhibitors may also be useful. This group may be exemplified by oryzacystatin and amylase inhibitors, such as those from wheat and barley.
- genes encoding lectins may confer additional or alternative insecticide properties.
- Lectins (originally termed phytohemagglutinins) are multivalent carbohydrate-binding proteins which have the ability to agglutinate red blood ceUs from a range of species. Lectins have been identified recently as insecticidal agents with activity against weevils, ECB and rootworm (Murdock et al., 1990; Czapla and Lang, 1990). Lectin genes contemplated to be useful include, for example, barley and wheat germ agglutinin (WGA) and rice lectins (Gatehouse et al., 1984), with WGA being prefened.
- WGA barley and wheat germ agglutinin
- rice lectins Greek being prefened.
- Genes controlling the production of large or small polypeptides active against insects when introduced into the insect pests form another aspect ofthe mvention.
- the expression of juvenile hormone esterase directed towards specific insect pests, may also result in insecticidal activity, or perhaps cause cessation of metamorphosis (Hammock et al., 1990).
- Transgenic plants expressing genes which encode enzymes that affect the integrity of the insect cuticle form yet another aspect ofthe invention.
- genes include those encodmg, e.g., chitinase, proteases, Upases and also genes for the production of nikkomycin, a compound that inhibits chitin synthesis, the introduction of any of which is contemplated to produce insect resistant maize plants.
- Genes that code for activities that affect insect molting, such those affecting the production of ecdysteroid UDP-glucosyl transferase also fall within the scope ofthe useful transgenes ofthe present invention.
- Genes that code for enzymes that facilitate the production of compounds that reduce the nutritional quality ofthe host plant to insect pests are also encompassed by the present invention. It may be possible, for instance, to confer insecticidal activity on a plant by altering its sterol composition. Sterols are obtained by insects from their diet and are used for hormone synthesis and membrane stability. Therefore alterations in plant sterol composition by expression of novel genes, e.g., those that directly promote the production of undesirable sterols or those that convert desirable sterols into undesirable forms, could have a negative effect on insect growth and/or development and hence endow the plant with insecticidal activity. Lipoxygenases are naturally occurring plant enzymes that have been shown to exhibit anti-nutritional effects on insects and to reduce the nutritional quality of their diet.
- transgenic plants with enhanced lipoxygenase activity which may be resistant to insect feeding.
- the present invention also provides methods and compositions by which to achieve qualitative or quantitative changes in plant secondary metabolites.
- One example concerns transforming plants to produce DIMBOA which, it is contemplated, wdl confer resistance to European corn borer, rootworm and several other maize insect pests.
- Candidate genes that are particularly considered for use in this regard include those genes at the bx locus known to be involved in the synthetic DIMBOA pathway (Dunn et al., 1981).
- Tripsacum dactyloides is a species of grass that is resistant to certain insects, including corn root worm. It is anticipated that genes encoding proteins that are toxic to insects or are involved in the biosynthesis of compounds toxic to insects will be isolated from Tripsacum and that these novel genes will be useful in confening resistance to insects. It is known that the basis of insect resistance in Tripsacum is genetic, because said resistance has been transfened to Zea mays via sexual crosses (Branson and Guss, 1972).
- genes encoding proteins characterized as having potential insecticidal activity may also be used as transgenes in accordance herewith.
- Such genes include, for example, the cowpea trypsin inhibitor (CpTI; Hilder et al., 1987) which may be used as a rootworm detenent; genes encoding avermectin (Campbell, 1989; Ikeda et al., 1987) which may prove particularly useful as a corn rootworm detenent; ribosome inactivating protein genes; and even genes that regulate plant stractures.
- Transgenic maize including anti-insect antibody genes and genes that code for enzymes that can covert a non-toxic insecticide (pro-insecticide) applied to the outside ofthe plant into an insecticide inside the plant are also contemplated.
- pro-insecticide non-toxic insecticide
- 3. Environment or Stress Resistance Improvement of a plant's ability to tolerate various environmental stresses such as, but not limited to, drought, excess moisture, chilling, freezing, high temperature, salt, and oxidative stress, can also be effected through expression of heterologous, or overexpression of homologous genes. Benefits may be realized in terms of increased resistance to freezing temperatures through the introduction of an "antifreeze" protein such as that ofthe Winter Flounder (Cutler et al., 1989) or synthetic gene derivatives thereof.
- Improved chilling tolerance may also be confened through increased expression of glycerol-3-phosphate acetyltransferase in chloroplasts (Murata et al., 1992; Wolter et al., 1992).
- Resistance to oxidative stress can be confened by expression of superoxide dismutase (Gupta et al., 1993), and may be improved by glutathione reductase (Bowler et al., 1992).
- Such strategies may allow for tolerance to freezing in newly emerged fields as well as extending later maturity higher yielding varieties to earlier relative maturity zones.
- drought resistance and “drought tolerance” are used to refer to a plants increased resistance or tolerance to stress induced by a reduction in water availability, as compared to normal circumstances, and the ability ofthe plant to function and survive in lower-water environments, and perform in a relatively superior manner.
- the expression of a gene encoding the biosynthesis of osmotically-active solutes can impart protection against drought.
- Naturally occurring metabolites that are osmotically active and/or provide some direct protective effect during drought and/or desiccation include sugars and sugar derivatives such as fructose, erythritol (Coxson et al., 1992), sorbitol, dulcitol (Karsten et al., 1992), glucosylglycerol (Reed et al., 1984; Erdmann et al., 1992), sucrose, stachyose (Koster and Leopold, 1988; Blackman et al., 1992), ononitol and pinitol (Vernon and Bohnert, 1992), and raffinose (Bernal-Lugo and Leopold, 1992).
- sugars and sugar derivatives such as fructose, erythritol (Coxson et al., 1992), sorbitol, dulcitol (Karsten et al., 1992), glucosylglycerol
- osmotically active solutes which are not sugars include, but are not limited to, proline and glycine-betaine (Wyn- Jones and Storey, 1981).
- proline and glycine-betaine Widen- Jones and Storey, 1981.
- genes such as those controlling the osmotically active compounds discussed above and other such compounds, as represented in one exemplary embodiment by the enzyme myoinositol 0-methyltransferase.
- Late Embryogenic Proteins have been assigned based on structural similarities (see Dure et al., 1989). AU three classes of these proteins have been demonstrated in maturing (i.e., desiccating) seeds. Within these 3 types of proteins, the Type-II (dehydrin- type) have generally been implicated in drought and/or desiccation tolerance in vegetative plant parts (i.e. Mundy and Chua, 1988; Piatkowski et al., 1990; Yamaguchi-Shinozaki et al., 1992). Recently, expression of a Type-Ill LEA (HVA-1) in tobacco was found to influence plant height, maturity and drought tolerance (Fitzpatrick, 1993).
- HVA-1 Type-Ill LEA
- stractural genes from all three groups may therefore confer drought tolerance.
- Other types of proteins induced during water stress include thiol proteases, aldolases and transmembrane transporters (Guenero et al., 1990), which may confer various protective and/or repair-type functions during drought stress.
- the expression of a gene that effects lipid biosynthesis and hence membrane composition can also be useful in conferring drought resistance on the plant.
- genes that are involved with specific morphological traits that allow for increased water extractions from drying soil would be of benefit. For example, introduction and expression of genes that alter root characteristics may enhance water uptake. Expression of genes that enhance reproductive fitness during times of stress would be of significant value. For example, expression of DNAs that improve the synchrony of pollen shed and receptiveness ofthe female flower parts, i.e., silks, would be of benefit. In addition, expression of genes that minimize kernel abortion during times of stress would increase the amount of grain to be harvested and hence be of value. Regulation of cytokinin levels in monocots, such as maize, by introduction and expression of an isopentenyl transferase gene with appropriate regulatory sequences can improve monocot stress resistance and yield (Gan et al., Science. 270: 1986 (1995)).
- a viral coat protein in a transgenic plant can impart resistance to infection ofthe plant by that virus and perhaps other closely related viruses (Cuozzo et al., 1988, Hemenway et al., 1988, Abel et al., 1986). It is contemplated that expression of antisense genes targeted at essential viral functions may impart resistance to said viras. For example, an antisense gene targeted at the gene responsible for replication of viral nucleic acid may inhibit said replication and lead to resistance to the virus. It is believed that interference with other viral functions through the use of antisense genes may also increase resistance to viruses. Further it is proposed that it may be possible to achieve resistance to viruses through other approaches, including, but not limited to the use of satellite viruses.
- Peptide antibiotics are polypeptide sequences which are inhibitory to growth of bacteria and other microorganisms.
- PR proteins pathogenesis related proteins
- toxin resistance proteins affecting host-pathogen interactions
- proteins affecting host-pathogen interactions such as morphological characteristics
- Peptide antibiotics are polypeptide sequences which are inhibitory to growth of bacteria and other microorganisms.
- the classes of peptides refened to as cecropins and magainins inhibit growth of many species of bacteria and fungi. It is proposed that expression of PR proteins in plants may be useful in confening resistance to bacterial disease.
- genes are induced following pathogen attack on a host plant and have been divided into at least five classes of proteins (Bol et al., 1990). Included amongst the PR proteins are beta-1,3- glucanases, chitinases, and osmotin and other proteins that are believed to function in plant resistance to disease organisms. Other genes have been identified that have antifungal properties, e.g., UDA (stinging nettle lectin) and hevein (Broakgert et al., 1989; Barkai-Golan et al., 1978). It is known that certain plant diseases are caused by the production of phytotoxins.
- UDA stinging nettle lectin
- hevein Broakgert et al., 1989; Barkai-Golan et al., 1978. It is known that certain plant diseases are caused by the production of phytotoxins.
- Resistance to these diseases could be achieved through expression of a novel gene that encodes an enzyme capable of degrading or otherwise inactivating the phytotoxin.
- Expression novel genes that alter the interactions between the host plant and pathogen may be useful in reducing the ability the disease organism to invade the tissues ofthe host plant, e.g., an increase in the waxiness ofthe leaf cuticle or other morphological characteristics.
- Plant parasitic nematodes are a cause of disease in many plants. It is proposed that it would be possible to make the plant resistant to these organisms through the expression of novel genes.
- mycotoxins including aflatoxin and fumonisin
- fungi associated with plants are a significant factor in rendering the grain not useful.
- These fungal organisms do not cause disease symptoms and/or interfere with the growth ofthe plant, but they produce chemicals (mycotoxins) that are toxic to animals. Inhibition ofthe growth of these fungi would reduce the synthesis of these toxic substances and, therefore, reduce grain losses due to mycotoxin contamination.
- Novel genes may be introduced into plants that would inhibit synthesis ofthe mycotoxin without interfering with fungal growth. Expression of a novel gene which encodes an enzyme capable of rendering the mycotoxin nontoxic would be useful in order to achieve reduced mycotoxin contamination of grain. The result of any ofthe above mechanisms would be a reduced presence of mycotoxins on grain. 6. Grain Composition or Quality
- Genes may be introduced into plants, particularly commercially important cereals such as maize, wheat or rice, to improve the grain for which the cereal is primarily grown.
- a wide range of novel transgenic plants produced in this manner may be envisioned depending on the particular end use ofthe grain.
- maize grain For example, the largest use of maize grain is for feed or food. Introduction of genes that alter the composition ofthe grain may greatly enhance the feed or food value.
- the primary components of maize grain are starch, protein, and oil. Each of these primary components of maize grain may be improved by altering its level or composition. Several examples may be mentioned for illustrative purposes but in no way provide an exhaustive list ofpossibilities.
- the protein of many cereal grains is suboptimal for feed and food purposes especially when fed to pigs, poultry, and humans.
- the protein is deficient in several amino acids that are essential in the diet of these species, requiring the addition of supplements to the grain.
- Limiting essential amino acids may include lysine, methionine, tryptophan, threonine, valine, arginine, and histidine.
- Some amino acids become limiting only after the grain, is supplemented with other inputs for feed formulations. For example, when the grain is supplemented with soybean meal to meet lysine requirements, methionine becomes limiting.
- the levels of these essential amino acids in seeds and grain may be elevated by mechanisms which include, but are not limited to, the introduction of genes to increase the biosynthesis of the amino acids, decrease the degradation ofthe amino acids, increase the storage ofthe amino acids in proteins, or increase transport ofthe amino acids to the seeds or grain.
- One mechanism for increasing the biosynthesis ofthe amino acids is to introduce genes that deregulate the amino acid biosynthetic pathways such that the plant can no longer adequately control the levels that are produced. This may be done by deregulating or bypassing steps in the amino acid biosynthetic pathway which are normally regulated by levels ofthe amino acid end product ofthe pathway.
- Examples include the introduction of genes that encode deregulated versions ofthe enzymes aspartokinase or dihydrodipicolinic acid (DHDP)- synthase for increasing lysine and threonine production, and anthranilate synthase for increasing tryptophan production.
- Reduction ofthe catabolism ofthe amino acids may be accomplished by introduction of DNA sequences that reduce or eliminate the expression of genes encoding enzymes that catalyse steps in the catabolic pathways such as the enzyme lysine-ketoglutarate reductase.
- the protein composition ofthe grain may be altered to improve the balance of amino acids in a variety of ways including elevating expression of native proteins, decreasing expression of those with poor composition, changing the composition of native proteins, or introducing genes encoding entirely new proteins possessing superior composition.
- DNA may be introduced that decreases the expression of members ofthe zein family of storage proteins. This DNA may encode ribozymes or antisense sequences directed to impairing expression of zein proteins or expression of regulators of zein expression such as the opaque-2 gene product.
- the protein composition ofthe grain may be modified through the phenomenon of cosuppression, i.e., inhibition of expression of an endogenous gene tlirough the expression of an identical stractural gene or gene fragment introduced through transformation (Goring et al., 1991).
- the introduced DNA may encode enzymes which degrade seines.
- the decreases in zein expression that are achieved may be accompanied by increases in proteins with more desirable amino acid composition or increases in other major seed constituents such as starch.
- a chimeric gene may be introduced that comprises a coding sequence for a native protein of adequate amino acid composition such as for one ofthe globulin proteins or 10 kD zein of maize and a promoter or other regulatory sequence designed to elevate expression of said protein.
- the coding sequence of said gene may include additional or replacement codons for essential amino acids.
- a coding sequence obtained from another species, or, a partially or completely synthetic sequence encoding a completely unique peptide sequence designed to enhance the amino acid composition ofthe seed may be employed.
- genes that alter the oil content ofthe grain may be of value. Increases in oil content may result in increases in metabohzable energy content and density of the seeds for uses in feed and food.
- the introduced genes may encode enzymes that remove or reduce rate-limitations or regulated steps in fatty acid or lipid biosynthesis. Such genes may include, but are not limited to, those that encode acetyl-CoA carboxylase, ACP-acyltransferase, beta-ketoacyl-ACP synthase, plus other well known fatty acid biosynthetic activities. Other possibilities are genes that encode proteins that do not possess enzymatic activity such as acyl canier protein.
- Additional examples include 2-acetyltransferase, oleosin pyruvate dehydrogenase complex, acetyl CoA synthetase, ATP citrate lyase, ADP-glucose pyrophosphorylase and genes ofthe carnitine-CoA- acetyl-CoA shuttles. It is anticipated that expression of genes related to oil biosynthesis will be targeted to the plastid, using a plastid transit peptide sequence and preferably expressed in the seed embryo. Genes may be introduced that alter the balance of fatty acids present in the oil providing a more healthful or nutritive feedstuff.
- the introduced DNA may also encode sequences that block expression of enzymes involved in fatty acid biosynthesis, altering the proportions of fatty acids present in the grain such as described below.
- Genes may be introduced that enhance the nutritive value ofthe starch component of the grain, for example by increasing the degree of branching, resulting in improved utilization ofthe starch in cows by delaying its metabolism.
- genes may be introduced that affect a variety of other nutritive, processing, or other quality aspects ofthe grain as used for feed or food. For example, pigmentation ofthe grain may be increased or decreased.
- Enhancement and stability of yellow pigmentation is desirable in some animal feeds and may be achieved by introduction of genes that result in enhanced production of xanthophylls and carotenes by eliminating rate-limiting steps in their production.
- genes may encode altered forms ofthe enzymes phytoene synthase, phytoene desaturase, or lycopene synthase.
- unpigmented white corn is desirable for production of many food products and may be produced by the introduction of DNA which blocks or eliminates steps in pigment production pathways.
- Feed or food comprising some cereal grains possesses insufficient quantities of vitamins and must be supplemented to provide adequate nutritive value.
- Introduction of genes that enhance vitamin biosynthesis in seeds may be envisioned including, for example, vitamins A, E, B 12 , choline, and the like.
- maize grain also does not possess sufficient mineral content for optimal nutritive value.
- Genes that affect the accumulation or availability of compounds containing phosphoras, sulfur, calcium, manganese, zinc, and iron among others would be valuable.
- An example may be the introduction of a gene that reduced phytic acid production or encoded the enzyme phytase which enhances phytic acid breakdown. These genes would increase levels of available phosphate in the diet, reducing the need for supplementation with mineral phosphate.
- Improvement of cereals for feed and food purposes might be described.
- the improvements may not even necessarily involve the grain, but may, for example, improve the value ofthe grain for silage.
- Introduction of DNA to accomplish this might include sequences that alter lignin production such as those that result in the "brown midrib" phenotype associated with superior feed value for cattle.
- genes may also be introduced which improve the processing of grain and improve the value ofthe products resulting from the processing.
- the primary method of processing certain grains such as maize is via wetmilling. Maize may be improved though the expression of novel genes that increase the efficiency and reduce the cost of processing such as by decreasing steeping time.
- Improving the value of wetmilling products may include altering the quantity or quality of starch, oil, corn gluten meal, or the components of corn gluten feed. Elevation of starch may be achieved through the identification and elimination of rate limiting steps in starch biosynthesis or by decreasing levels ofthe other components ofthe grain resulting in proportional increases in starch.
- An example ofthe former may be the introduction of genes encoding ADP-glucose pyrophosphorylase enzymes with altered regulatory activity or which are expressed at higher level.
- Examples ofthe latter may include selective inhibitors of, for example, protein or oil biosynthesis expressed during later stages of kernel development.
- the properties of starch may be beneficially altered by changing the ratio of amylose to amylopectin, the size ofthe starch molecules, or their branching pattern.
- a broad range of properties may be modified which include, but are not limited to, changes in gelatinization temperature, heat of gelatinization, clarity of films and pastes, Theological properties, and the like.
- genes that encode granule-bound or soluble starch synthase activity or branching enzyme activity may be introduced alone or combination. DNA such as antisense constructs may also be used to decrease levels of endogenous activity of these enzymes.
- the introduced genes or constracts may possess regulatory sequences that time their expression to specific intervals in starch biosynthesis and starch granule development.
- glucose moieties ofthe starch molecule may be advisable to introduce and express genes that result in the in vivo derivatization, or other modification, ofthe glucose moieties ofthe starch molecule.
- the covalent attachment of any molecule may be envisioned, limited only by the existence of enzymes that catalyze the derivatizations and the accessibility of appropriate substrates in the starch granule.
- important derivations may include the addition of functional groups such as amines, carboxyls, or phosphate groups which provide sites for subsequent in vitro derivatizations or affect starch properties through the introduction of ionic charges.
- modifications may include direct changes of the glucose units such as loss of hydroxyl groups or their oxidation to aldehyde or carboxyl groups.
- Oil is another product of wetmilling of corn and other grains, the value of which may be improved by introduction and expression of genes.
- the quantity of oil that can be extracted by wetmilling may be elevated by approaches as described for feed and food above.
- Oil properties may also be altered to improve its performance in the production and use of cooking oil, shortenings, lubricants or other oil-derived products or improvement of its health attributes when used in the food-related applications.
- Novel fatty acids may also be synthesized which upon extraction can serve as starting materials for chemical syntheses.
- the changes in oil properties may be achieved by altering the type, level, or lipid arrangement ofthe fatty acids present in the oil.
- This in rum may be accomplished by the addition of genes that encode enzymes that catalyze the synthesis of novel fatty acids and the lipids possessing them or by increasing levels of native fatty acids while possibly reducing levels of precursors.
- DNA sequences may be introduced which slow or block steps in fatty acid biosynthesis resulting in the increase in precursor fatty acid intermediates.
- Genes that might be added include desaturases, epoxidases, hydratases, dehydratases, and other enzymes that catalyze reactions involving fatty acid intermediates.
- Representative examples of catalytic steps that might be blocked include the desaturations from stearic to oleic acid and oleic to linolenic acid resulting in the respective accumulations of stearic and oleic acids.
- Improvements in the other major cereal wetmilling products, gluten meal and gluten feed may also be achieved by the introduction of genes to obtain novel plants. Representative possibilities include but are not limited to those described above for improvement of food and feed value.
- the plant be used for the production or manufacturing of useful biological compounds that were either not produced at all, or not produced at the same level, in the plant previously.
- the novel plants producing these compounds are made possible by the introduction and expression of genes by transformation methods.
- the possibilities include, but are not limited to, any biological compound which is presently produced by any organism such as proteins, nucleic acids, primary and intermediary metabolites, carbohydrate polymers, etc.
- the compounds may be produced by the plant, extracted upon harvest and/or processing, and used for any presently recognized useful purpose such as pharmaceuticals, fragrances, industrial enzymes to name a few.
- Two ofthe factors determining where plants can be grown are the average daily temperature during the growing season and the length of thne between frosts.
- the plant to be grown in a particular area is selected for its ability to mature and dry down to harvestable moisture content within the required period of time with maximum possible yield. Therefore, plant of varying maturities are developed for different growing locations. Apart from the need to dry down sufficiently to permit harvest is the desirability of having maximal drying take place in the field to miriimize the amount of energy required for additional drying post-harvest. Also the more readily the grain can dry down, the more time there is available for growth and kernel fill.
- Genes that influence maturity and/or dry down can be identified and introduced into plant lines using transformation techniques to create new varieties adapted to different growing locations or the same growing location but having improved yield to moisture ratio at harvest.
- Expression of genes that are involved in regulation of plant development may be especially useful, e.g., the liguleless and rough sheath genes that have been identified in plants.
- Genes may be introduced into plants that would improve standability and other plant growth characteristics. For example, expression of novel genes which confer stronger stalks, improved root systems, or prevent or reduce ear droppage would be of great value to the com farmer. Introduction and expression of genes that increase the total amount of photoassimilate available by, for example, increasing light distribution and/or interception would be advantageous. In addition the expression of genes that increase the efficiency of photosynthesis and/or the leaf canopy would further increase gains in productivity. Such approaches would allow for increased plant populations in the field.
- male sterility is useful in the production of hybrid seed. It is proposed that male sterility may be produced through expression of novel genes. For example, it has been shown that expression of genes that encode proteins that interfere with development ofthe male inflorescence and/or gametophyte result in male sterility. Chimeric ribonuclease genes that express in the anthers of transgenic tobacco and oilseed rape have been demonstrated to lead to male sterility (Mariani et al, 1990).
- genes encoding traits that can be selected against may be useful for eliminating undesirable linked genes.
- the genes will be linked together on the host chromosome.
- a gene encoding a Bt gene that confers insect resistance on the plant may be introduced into a plant together with a bar gene that is useful as a selectable marker and confers resistance to the herbicide Ignite® on the plant.
- a bar gene that is useful as a selectable marker and confers resistance to the herbicide Ignite® on the plant may not be desirable to have an insect resistant plant that is also resistant to the herbicide Ignite®. It is proposed that one could also introduce an antisense bar gene that is expressed in those tissues where one does not want expression of the bar gene, e.g., in whole plant parts.
- the bar antisense gene is a negative selectable marker. Negative selection is necessary in order to screen a population of transformants for rare homologous recombinants generated through gene targeting. For example, a homologous recombinant may be identified through the inactivation of a gene that was previously expressed in that cell.
- the antisense gene to neomycin phosphotransferase II (nptll) has been investigated as a negative selectable marker in tobacco (Nicotiana tabacum) and Arabidopsis thaliana (Xiang and Guena, 1993).
- both sense and antisense nptll genes are introduced into a plant through transformation and the resultant plants are sensitive to the antibiotic kanamycin.
- An introduced gene that integrates into the host cell chromosome at the site ofthe antisense nptll gene, and inactivates the antisense gene, will make the plant resistant to kanamycin and other aminoglycoside antibiotics. Therefore, rare site specific recombinants may be identified by screening for antibiotic resistance.
- any gene, native to the plant or introduced through transformation, that when inactivated confers resistance to a compound may be useful as a negative selectable marker.
- negative selectable markers may also be useful in other ways.
- One application is to construct transgenic lines in which one could select for transposition to unlinked sites. In the process of tagging it is most common for the transposable element to move to a genetically linked site on the same chromosome.
- a selectable marker for recovery of rare plants in which transposition has occurred to an unlinked locus would be useful.
- the enzyme cytosine deaminase may be useful for this purpose (Stouggard, 1993). In the presence of this enzyme the compound 5-fluorocytosine is converted to 5-fluoraracil which is toxic to plant and animal cells.
- transposable element is linked to the gene for the enzyme cytosine deaminase
- the parental plants and plants containing transpositions to linked sites will remain sensitive to 5- fluorocytosine.
- Resistance to 5-fluorocytosine is due to loss ofthe cytosine deaminase gene through genetic segregation ofthe transposable element and the cytosine deaminase gene.
- Other genes that encode proteins that render the plant sensitive to a certain compound will also be useful in this context.
- T-DNA gene 2 from Agrobacterium tumefaciens encodes a protein that catalyzes the conversion of alpha-naphthalene acetamide (NAM) to alpha-napthalene acetic acid (NAA) renders plant cells sensitive to high concentrations of NAM (Depicker et al., 1988).
- NAM alpha-naphthalene acetamide
- NAA alpha-napthalene acetic acid
- negative selectable markers may be useful in the construction of transposon tagging lines.
- an autonomous transposable element such as Ac, Master Mu, or En/Spn
- a negative selectable marker By marking an autonomous transposable element such as Ac, Master Mu, or En/Spn with a negative selectable marker, one could select for transformants in which the autonomous element is not stably integrated into the genome. This would be desirable, for example, when transient expression ofthe autonomous element is desired to activate in trans the transposition of a defective transposable element, such as Ds, but stable integration ofthe autonomous element is not desired. The presence ofthe autonomous element may not be desired in order to stabilize the defective element, i.e., prevent it from further transposing. However, it is proposed that if stable integration of an autonomous transposable element is desired in a plant the presence of a negative selectable marker may make it possible to eliminate the autonomous element during the breeding process .
- Non-Protein-Expressing Sequences may be introduced into plants for the purpose of expressing RNA transcripts that function to affect plant phenotype yet are not translated into protein. Two examples are antisense RNA and RNA with ribozyme activity. Both may serve possible functions in reducing or eliminating expression of native or introduced plant genes.
- Genes may be constructed or isolated, which when transcribed, produce antisense RNA that is complementary to all or part(s) of a targeted messenger RNA(s).
- the antisense RNA reduces production ofthe polypeptide product ofthe messenger RNA.
- the polypeptide product may be any protein encoded by the plant genome.
- the aforementioned genes will be refened to as antisense genes.
- An antisense gene may thus be introduced into a plant by transformation methods to produce a novel transgenic plant with reduced expression of a selected protein of interest.
- the protein may be an enzyme that catalyzes a reaction in the plant.
- Reduction ofthe enzyme activity may reduce or eliminate products ofthe reaction which include any enzymatically synthesized compound in the plant such as fatty acids, amino acids, carbohydrates, nucleic acids and the like.
- the protein may be a storage protein, such as a zein, or a stractural protein, the decreased expression of which may lead to changes in seed amino acid composition or plant morphological changes respectively.
- Genes may also be constracted or isolated, which when transcribed produce RNA enzymes, or ribozymes, which can act as endoribonucleases and catalyze the cleavage of RNA molecules with selected sequences. The cleavage of selected messenger RNA's can result in the reduced production of their encoded polypeptide products.
- These genes may be used to prepare novel transgenic plants which possess them.
- the transgenic plants may possess reduced levels of polypeptides including but not limited to the polypeptides cited above that may be affected by antisense RNA. It is also possible that genes may be introduced to produce novel transgenic plants which have reduced expression of a native gene product by a mechanism of cosuppression.
- Non-RNA-Expressing DNA elements including those of transposable elements such as Ds, Ac, or Mu, may be inserted into a gene and cause mutations.
- DNA elements may be inserted in order to inactivate (or activate) a gene and thereby "tag" a particular trait.
- the transposable element does not cause instability ofthe tagged mutation, because the utility ofthe element does not depend on its ability to move in the genome.
- the introduced DNA sequence may be used to clone the correspondmg gene, e.g., using the introduced DNA sequence as a PCR primer together with PCR gene cloning techniques (Shapiro, 1983; Dellaporta et al., 1988). Once identified, the entire gene(s) for the particular trait, including control or regulatory regions where desired may be isolated, cloned and manipulated as desired.
- DNA elements introduced into an organism for purposed of gene tagging is independent ofthe DNA sequence and does not depend on any biological activity ofthe DNA sequence, i.e., transcription into RNA or translation into protein.
- the sole function ofthe DNA element is to disrapt the DNA sequence of a gene.
- unexpressed DNA sequences including novel synthetic sequences could be introduced into cells as proprietary "labels" of those cells and plants and seeds thereof. It would not be necessary for a label DNA element to disrapt the function of a gene endogenous to the host organism, as the sole function of this DNA would be to identify the origin ofthe organism. For example, one could introduce a unique DNA sequence into a plant and this DNA element would identify all cells, plants, and progeny of these cells as having arisen from that labeled source. It is proposed that inclusion of label DNAs would enable one to distinguish proprietary germplasm or germplasm derived from such, from unlabelled germplasm.
- MAR matrix attachment region element
- Plants of the Invention and Methods of Preparation may be transformed with the DNA constract ofthe present invention by the DNA-mediated transformation of plant cell protoplasts and subsequent regeneration ofthe plant from the transformed protoplasts in accordance with procedures well known in the art.
- Any plant tissue capable of subsequent clonal propagation, whether by organogenesis or embryogenesis, may be transformed with a vector ofthe present invention.
- organogenesis means a process by which shoots and roots are developed sequentially from meristematic centers
- embryogenesis as used herein, means a process by which shoots and roots develop together in a concerted fashion (not sequentially), whether from somatic cells or gametes.
- tissue targets include leaf disks, pollen, embryos, cotyledons, hypocotyls, megagametophytes, callus tissue, existing meristematic tissue (e.g., apical meristems, axillary buds, and root meristems), and induced meristem tissue (e.g., cotyledon meristem and ultilane meristem).
- Plants ofthe present invention may take a variety of fonns.
- the plants may be chimeras of transformed cells and non-transformed cells; the plants may be clonal transformants (e.g., all cells transformed to contain the expression cassette); the plants may comprise grafts of transformed and untransformed tissues (e.g., a transformed root stock grafted to an untransformed scion in citrus species).
- the transformed plants may be propagated by a variety of means, such as by clonal propagation or classical breeding techniques. For example, first generation (or TI) transformed plants may be selfed to give homozygous second generation (or T2) transformed plants, and the T2 plants further propagated through classical breeding techniques.
- a dominant selectable marker (such as npt II) can be associated with the expression cassette to assist in breeding.
- the present invention provides a transformed (transgenic) plant cell, in planta or ex planta, including a transformed plastid or other organelle, e.g., nucleus, mitochondria or chloroplast.
- the present invention may be used for transformation of any plant species, including, but not limited to, cells from corn (Zea mays), Brassica sp. (e.g., B. napus, B.
- rapa, B.juncea particularly those Brassica species useful as sources of seed oil, alfalfa (Medicago sativa), rice (Oryza sativa), rye (Secale cereale), sorghum (Sorghum bicolor, Sorghum vulgare), millet (e.g., pearl millet (Pennisetum glaucum), proso millet (Panicum miliaceum), foxtail millet (Setaria italica), finger millet (Eleusine coracana)), sunflower (Helianthus annuus), safflower (Carthamus tinctorius), wheat (Triticum aestivum), soybean (Glycine max), tobacco (Nicotiana tabacum), potato (Solanum tuberosum), peanuts (Arachis hypogaea), cotton (Gossypium barbadense, Gossypium hirsutum), sweet potato (Ipomoea batatus), cassava (Man
- Duckweed (Lemna, see WO 00/07210) includes members ofthe family Lemnaceae. There are known four genera and 34 species of duckweed as follows: genus Lemna (L. aequinoctialis, L. disperma, L. ecuadoriensis, L. gibba, L. japonica, L. minor, L. miniscula, L. obscura, L. perpusilla, L. tenera, L. trisulca, L.turionifera, L. valdiviana); genus Spirodela (S. intermedia, S. polyrrhiza, S. punctata); genus Woffia (Wa. Angusta, Wa. Arrhiza, Wa.
- genus Lemna L. aequinoctialis, L. disperma, L. ecuadoriensis, L. gibba, L. japonica, L. minor, L. miniscula, L. obscur
- Lemna gibba, Lemna minor, and Lemna miniscula are prefened, with Lemna minor and Lemna miniscula being most prefened.
- Lemna species can be classified using the taxonomic scheme described by Landolt, Biosystematic Investigation on the Family of Duckweeds: The family of
- Vegetables within the scope ofthe invention include tomatoes (Lycopersicon esculentum), lettuce (e.g., Lactuca sativa), green beans (Phaseolus vulgaris), lima beans (Phaseolus limensis), peas (Lathyrus spp.), and members ofthe genus Cucumis such as cucumber (C. sativus), cantaloupe (C cantalupensis), and musk melon (C. melo).
- Ornamentals include azalea (Rhododendron spp.), hydrangea (Macrophylla hydrangea), hibiscus (Hibiscus rosasanensis), roses (Rosa spp.), tulips (Tulipa spp.), daffodils (Narcissus spp.), petunias (Petunia hybrida), carnation (Dianthus caryophyllus), poinsettia (Euphorbia pulcherrima), and chrysanthemum.
- Conifers that may be employed in practicing the present invention include, for example, pines such as loblolly pine (Pinus taeda), slash pine (Pinus elliotii), ponderosa pine (Pinus ponderosa), lodgepole pine (Pinus contorta), and Monterey pine (Pinus radiata), Douglas-fir (Pseudotsuga menziesii); Western hemlock (Tsuga ultilane); Sitka spruce (Picea glauca); redwood (Sequoia sempervirens); trae firs such as silver fir (Abies amabilis) and balsam fir (Abies balsamea); and cedars such as Western red cedar (Thuja plicata) and Alaska yellow-cedar (Chamaecyparis nootkatensis).
- pines such as loblolly pine (Pinus taeda), slash pine
- Leguminous plants include beans and peas.
- Beans include guar, locust bean, fenugreek, soybean, garden beans, cowpea, mungbean, lima bean, fava bean, lentils, chickpea, etc.
- Legumes include, but are not limited to, Arachis, e.g., peanuts, Vicia, e.g., crown vetch, hairy vetch, adzuki bean, mung bean, and chickpea, Lupinus, e.g., lupine, trifolium, Phaseolus, e.g., common bean and lima bean, Pisum, e.g., field bean, Melilotus, e.g., clover, Medicago, e.g., alfalfa, Lotus, e.g., trefoil, lens, e.g., lentil, and false indigo.
- Prefened forage and turfgrass for use in the methods ofthe invention include alfalfa, orchard grass, tall fescue, perennial ryegrass, creeping bent grass, and redtop.
- plants within the scope ofthe invention include Acacia, aneth, artichoke, aragula, blackberry, canola, cilantro, Clementines, escarole, eucalyptus, fennel, grapefruit, honey dew, jicama, kiwifiuit, lemon, lime, mushroom, nut, okra, orange, parsley, pers rimon, plantain, pomegranate, poplar, radiata pine, radicchio, Southern pine, sweetgum, tangerine, triticale, vine, yams, apple, pear, quince, cherry, apricot, melon, hemp, buckwheat, grape, raspberry, chenopodium, blueberry, nectarine, peach, plum, strawberry, watermelon, eggplant, pepper, cauliflower, Brassica, e.g., broccoli, cabbage, ultilan sprouts, onion, canot, leek, beet, broad bean, celery,
- Ornamental plants within the scope ofthe invention include impatiens, Begonia, Pelargonium, Viola, Cyclamen, Verbena, Vinca, Tagetes, Primula, Saint Paulia, Agertum, Amaranthus, Ajitihirrhinum, Aquilegia, Cineraria, Clover, Cosmo, Cowpea, Dahlia, Datura, Delphinium, Gerbera, Gladiolus, Gloxinia, Hippeastrum, Mesembryanthemum, Salpiglossos, and Zinnia. Other plants within the scope ofthe invention are shown in Table 1 (above).
- transgenic plants ofthe present invention are crop plants and in particular cereals (for example, corn, alfalfa, sunflower, rice, Brassica, canola, soybean, barley, soybean, sugarbeet, cotton, safflower, peanut, sorghum, wheat, millet, tobacco, etc.), and even more preferably corn, rice and soybean.
- cereals for example, corn, alfalfa, sunflower, rice, Brassica, canola, soybean, barley, soybean, sugarbeet, cotton, safflower, peanut, sorghum, wheat, millet, tobacco, etc.
- Transformation of plants can be undertaken with a single DNA molecule or multiple DNA molecules (i.e., co-transformation), and both these techniques are suitable for use with the expression cassettes ofthe present invention.
- Numerous transformation vectors are available for plant transformation, and the expression cassettes of this invention can be used in conjunction with any such vectors. The selection of vector will depend upon the prefened transformation technique and the target species for transformation.
- a variety of techniques are available and known to those skilled in the art for introduction of constracts into a plant cell host. These techniques generally include transfonnation with DNA employing A. tumefaciens or A. rhizogenes as the transforming agent, liposomes, PEG precipitation, electroporation, DNA injection, direct DNA uptake, microprojectile bombardment, particle acceleration, and the like (See, for example, EP 295959 and EP 138341) (see below). However, cells other than plant cells may be transformed with the expression cassettes ofthe invention.
- the general descriptions of plant expression vectors and reporter genes, and Agrobacterium and Agrobacterium-mediated gene transfer, can be found in Gruber et al. (1993).
- Expression vectors containing genomic or synthetic fragments can be introduced into protoplasts or into intact tissues or isolated cells.
- expression vectors are introduced into intact tissue.
- General methods of culturing plant tissues are provided for example by Maki et al., (1993); and by Phillips et al. (1988).
- expression vectors are introduced into maize or other plant tissues using a direct gene transfer method such as microprojectile- mediated delivery, DNA injection, electroporation and the like. More preferably expression vectors are introduced into plant tissues using the microprojectile media delivery with the biolistic device. See, for example, Tomes et al. (1995).
- the vectors ofthe invention can not only be used for expression of stractural genes but may also be used in exon-trap cloning, or promoter trap procedures to detect differential gene expression in varieties of tissues, (Lindsey et al., 1993; Auch & Reth et al.). It is particularly prefened to use the binary type vectors of Ti and Ri plasmids of
- Agrobacterium spp. Ti-derived vectors transform a wide variety of higher plants, including monocotyledonous and dicotyledonous plants, such as soybean, cotton, rape, tobacco, and rice (Pacciotti et al., 1985: Byrne et al., 1987; Sukhapinda et al., 1987; Park et al., 1985: Hiei et al., 1994).
- the use of T-DNA to transform plant cells has received extensive study and is amply described (EP 120516; Hoekema, 1985; Knauf, et al., 1983; and An et al., 1985).
- the chimeric genes ofthe invention can be inserted into binary vectors as described in the examples.
- transformation methods are available to those skilled in the art, such as direct uptake of foreign DNA constracts (see EP 295959), techniques of electroporation (Fromm et al., 1986) or high velocity ballistic bombardment with metal particles coated with the nucleic acid constracts (Kline et al., 1987, and U.S. Patent No. 4,945,050). Once transformed, the cells can be regenerated by those skilled in the art.
- rapeseed (De Block et al., 1989), sunflower (Everett et al., 1987), soybean (McCabe et al., 1988; Hinchee et al, 1988; Chee et al., 1989; Christou et al., 1989; EP 301749), rice (Hiei et al., 1994), and corn (Gordon Kamm et al., 1990; Fromm et al., 1990).
- Suitable methods of transforming plant cells include, but are not limited to, microinjection (Crossway et al., 1986), electroporation (Riggs et al., 1986), Agrobacterium-mediated transformation (Hinchee et al., 1988), direct gene transfer (Paszkowski et al., 1984), and ballistic particle acceleration using devices available from Agracetus, Inc., Madison, Wis. And BioRad, Hercules, Calif, (see, for example, Sanford et al., U.S. Pat. No.
- the protoplast transformation method for maize is employed (European Patent Application EP 0 292435, U. S. Pat. No. 5,350,689).
- a nucleotide sequence ofthe present invention is directly transformed into the plastid genome. Plastid transformation technology is extensively described in U.S. Patent Nos. 5,451,513, 5,545,817, and 5,545,818, in PCT application no. WO 95/16783, and in McBride et al., 1994.
- the basic technique for chloroplast transformation involves introducing regions of cloned plastid DNA flariking a selectable marker together with the gene of interest into a suitable target tissue, e.g., using biolistics or protoplast transformation (e.g., calcium chloride or PEG mediated transformation).
- a suitable target tissue e.g., using biolistics or protoplast transformation (e.g., calcium chloride or PEG mediated transformation).
- the 1 to 1.5 kb flanking regions termed targeting sequences, facilitate orthologous recombination with the plastid genome and thus allow the replacement or modification of specific regions ofthe plastome.
- Plastid expression in which genes are inserted by orthologous recombination into all ofthe several thousand copies ofthe circular plastid genome present in each plant cell, takes advantage of the eno ⁇ nous copy number advantage over nuclear-expressed genes to penriit expression levels that can readily exceed 10% ofthe total soluble plant protein.
- a nucleotide sequence ofthe present invention is inserted into a plastid targeting vector and transformed into the plastid genome of a desired plant host. Plants homoplastic for plastid genomes containing a nucleotide sequence ofthe present invention are obtained, and are preferentially capable of high expression ofthe nucleotide sequence.
- Agrobacterium tumefaciens cells containing a vector comprising an expression cassette ofthe present invention, wherein the vector comprises a Ti plasmid are useful in methods of making transformed plants. Plant cells are infected with an Agrobacterium tumefaciens as described above to produce a transformed plant cell, and then a plant is regenerated from the transformed plant cell. Numerous Agrobacterium vector systems useful in carrying out the present invention are known.
- vectors are available for transformation using Agrobacterium tumefaciens. These typically carry at least one T-DNA border sequence and include vectors such as pBIN19 (Bevan, 1984).
- the expression cassettes ofthe present invention may be inserted into either ofthe binary vectors pCIB200 and pCIB2001 for use with Agrobacterium. These vector cassettes for Agrobacterium-mediated transformation wear constracted in the following manner.
- PTJS75kan was created by Narl digestion of pTJS75 (Schmidhauser & Helinski, 1985) allowing excision ofthe tetracycline-resistance gene, followed by insertion of an Accl fragment from pUC4K carrying an NPTII (Messing & Vierra, 1982; Bevan et al., 1983; McBride et al., 1990).
- Xhol linkers were ligated to the
- PCIB200 contains the following unique polylinker restriction sites: EcoRI, Sstl, Kpnl, Bglll, Xbal, and Sail.
- the plasmid pCIB2001 is a derivative of pCIB200 which was created by the insertion into the polylinker of additional restriction sites.
- Unique restriction sites in the polylinker of pCIB2001 are EcoRI, Sstl, Kpnl, Bglll, Xbal, Sail, M , Bell, Avrll, Apal, Hpal, and Stul. PCIB2001, in addition to containing these unique restriction sites also has plant and bacterial kanamycin selection, left and right T-DNA borders for Agrobacterium-mediated transformation, the RK2-derived trfA function for mobilization between E. coli and other hosts, and the OriT and OriV functions also from RK2.
- the pCIB2001 polylinker is suitable for the cloning of plant expression cassettes containing their own regulatory signals.
- An additional vector useful fox Agrobacterium-mediated transformation is the binary vector pCIB 10, which contains a gene encoding kanamycin resistance for selection in plants, T-DNA right and left border sequences and incorporates sequences from the wide host- range plasmid pRK252 allowing it to replicate in both E. coli and Agrobacterium. Its construction is described by Rothstein et al., 1987.
- pCIBlO Various derivatives of pCIBlO have been constructed which incorporate the gene for hygromycin B phosphotransferase described by Gritz et al., 1983. These derivatives enable selection of transgenic plant cells on hygromycin only (pCIB743), or hygromycin and kanamycin (pCIB715, pCIB717).
- Methods using either a form of direct gene transfer ox Agrobacterium-mediated transfer usually, but not necessarily, are undertaken with a selectable marker which may provide resistance to an antibiotic (e.g., kanamycin, hygromycin or methotrexate) or a herbicide (e.g., phosphinothricin).
- a selectable marker which may provide resistance to an antibiotic (e.g., kanamycin, hygromycin or methotrexate) or a herbicide (e.g., phosphinothricin).
- antibiotic e.g., kanamycin, hygromycin or methotrexate
- a herbicide e.g., phosphinothricin
- selection markers used routinely in transformation include the nptll gene which confers resistance to kanamycin and related antibiotics (Messing & Vierra, 1982; Bevan et al., 1983), the bar gene which confers resistance to the herbicide phosphinothricin (White et al., 1990, Spencer et al., 1990), the hph gene which confers resistance to the antibiotic hygromycin (Blochinger & Diggelmann), and the dhfr gene, which confers resistance to methotrexate (Bourouis et al., 1983).
- pCIB3064 One such vector useful for direct gene transfer techniques in combination with selection by the herbicide Basta (or phosphinothricin) is pCIB3064.
- This vector is based on the plasmid pCIB246, which comprises the CaMV 35S promoter in operational fusion to the E. coli GUS gene and the CaMV 35S transcriptional terminator and is described in the PCT published application WO 93/07278, herein incorporated by reference.
- One gene useful for confening resistance to phosphinothricin is the bar gene from Streptomyces viridochromogenes (Thompson et al., 1987). This vector is suitable for the cloning of plant expression cassettes containing their own regulatory signals.
- An additional transformation vector is pSOG35 which utilizes the E. coli gene dihydrofolate reductase (DHFR) as a selectable marker confening resistance to methotrexate.
- PCR was used to amplify the 35S promoter (about 800 bp), intron 6 from the maize Adhl gene (about 550 bp) and 18 bp ofthe GUS untranslated leader sequence from pSOGlO. A 250 bp fragment encoding the E.
- coli dihydrofolate reductase type II gene was also amplified by PCR and these two PCR fragments were assembled with a Sacl-Pstl fragment from pBI221 (Clontech) which comprised the pUC 19 vector backbone and the nopaline synthase tenninator. Assembly of these fragments generated pSOG19 which contains the 35S promoter in fusion with the intron 6 sequence, the GUS leader, the DHFR gene and the nopaline synthase terminator. Replacement ofthe GUS leader in pSOG19 with the leader sequence from Maize Chlorotic Mottle Viras check (MCMV) generated the vector pSOG35.
- MCMV Maize Chlorotic Mottle Viras check
- pSOG19 and pSOG35 carry the pUC-derived gene for ampicillin resistance and have Hindlll, Sphl, Pstl and EcoRI sites available for the cloning of foreign sequences.
- Transgenic plant cells are then placed in an appropriate selective medium for selection of transgenic cells which are then grown to callus.
- Shoots are grown from callus and plantlets generated from the shoot by growing in rooting medium.
- the various constracts normally will be joined to a marker for selection in plant cells.
- the marker may be resistance to a biocide (particularly an antibiotic, such as kanamycin, G418, bleomycin, hygromycin, chloramphemcol, herbicide, or the like).
- DNA constracts including transcription cassettes of this invention may be prepared from sequences which are native (endogenous) or foreign (exogenous) to the host.
- foreign it is meant that the sequence is not found in the wild-type host into which the constract is introduced.
- Heterologous constracts will contain at least one region which is not native to the gene from which the transcription-initiation-region is derived.
- assays include, for example, "molecular biological” assays well known to those of skill in the art, such as Southern and Northern blotting, in situ hybridization and nucleic acid-based amplification methods such as PCR or RT-PCR; "biochemical” assays, such as detecting the presence of a protein product, e.g., by immunological means (ELISAs and Western blots) or by enzymatic function; plant part assays, such as leaf or root assays; and also, by analyzing the phenotype ofthe whole regenerated plant, e.g., for disease or pest resistance.
- DNA may be isolated from cell lines or any plant parts to determine the presence ofthe preselected nucleic acid segment through the use of techniques well known to those skilled in the art. Note that intact sequences will not always be present, presumably due to rearrangement or deletion of sequences in the cell.
- nucleic acid elements introduced through the methods of this invention may be determined by polymerase chain reaction (PCR). Using this technique discreet fragments of nucleic acid are amplified and detected by gel electrophoresis. This type of analysis permits one to determine whether a preselected nucleic acid segment is present in a stable transformant, but does not prove integration ofthe introduced preselected nucleic acid segment into the host cell genome. In addition, it is not possible using PCR techniques to determine whether transfo ⁇ nants have exogenous genes introduced into different sites in the genome, i.e., whether transformants are of independent origin. It is contemplated that using PCR techniques it would be possible to clone fragments ofthe host genomic DNA adjacent to an introduced preselected DNA segment.
- PCR polymerase chain reaction
- Positive proof of DNA integration into the host genome and the independent identities of transformants may be determined using the technique of Southern hybridization. Using this technique specific DNA sequences that were introduced into the host genome and flanking host DNA sequences can be identified. Hence the Southern hybridization pattern of a given transformant serves as an identifying characteristic of that transformant. In addition it is possible through Southern hybridization to demonstrate the presence of introduced preselected DNA segments in high molecular weight DNA, i.e., confirm that the introduced preselected DNA segment has been integrated into the host cell genome.
- the technique of Southern hybridization provides information that is obtained using PCR, e.g., the presence of a preselected DNA segment, but also demonstrates integration into the genome and characterizes each individual transformant.
- RNA may only be expressed in particular cells or tissue types and hence it will be necessary to prepare RNA for analysis from these tissues.
- PCR techniques may also be used for detection and quantitation of RNA produced from introduced preselected DNA segments. In this application of PCR it is first necessary to reverse transcribe RNA into DNA, using enzymes such as reverse transcriptase, and then through the use of conventional PCR techniques amplify the DNA. In most instances PCR techniques, while useful, will not demonstrate integrity ofthe RNA product. Further information about the nature ofthe RNA product may be obtained by Northern blotting. This technique will demonstrate the presence of an RNA species and give information about the integrity of that RNA. The presence or absence of an RNA species can also be determined using dot or slot blot Northern hybridizations. These techniques are modifications of Northern blotting and will only demonstrate the presence or absence of an RNA species.
- Southern blotting and PCR may be used to detect the preselected DNA segment in question, they do not provide information as to whether the preselected DNA segment is being expressed. Expression may be evaluated by specifically identifying the protein products ofthe introduced preselected DNA segments or evaluating the phenotypic changes brought about by their expression.
- Assays for the production and identification of specific proteins may make use of physical-chemical, stractural, functional, or other properties ofthe proteins.
- Unique physical- chemical or structural properties allow the proteins to be separated and identified by electrophoretic procedures, such as native or denaturing gel electrophoresis or isoelectric focusing, or by chromatographic techniques such as ion exchange or gel exclusion chromatography.
- the unique stractures of individual proteins offer opportunities for use of specific antibodies to detect their presence in formats such as an ELISA assay.
- Combinations of approaches may be employed with even greater specificity such as Western blotting in which antibodies are used to locate individual gene products that have been separated by electrophoretic techniques. Additional techniques may be employed to absolutely confirm the identity ofthe product of interest such as evaluation by amino acid sequencing following purification. Although these are among the most commonly employed, other procedures may be additionally used.
- Assay procedures may also be used to identify the expression of proteins by their functionality, especially the ability of enzymes to catalyze specific chemical reactions involving specific substrates and products. These reactions may be followed by providing and quantifying the loss of substrates or the generation of products ofthe reactions by physical or chemical procedures. Examples are as varied as the enzyme to be analyzed.
- the genetic properties engineered into the transgenic seeds and plants described above are passed on by sexual reproduction and can thus be maintained and propagated in progeny plants.
- the present invention also relates to a transgenic plant cell, tissue, organ, seed or plant part obtained from the transgenic plant. Also included within the invention are transgenic descendants ofthe plant as well as transgenic plant cells, tissues, organs, seeds and plant parts obtained from the descendants.
- the expression cassette in the transgenic plant is sexually transmitted.
- the coding sequence is sexually transmitted through a complete normal sexual cycle ofthe R0 plant to the Rl generation.
- the expression cassette is expressed in the cells, tissues, seeds or plant of a transgenic plant in an amount that is different than the amount in the cells, tissues, seeds or plant of a plant which only differs in that the expression cassette is absent.
- Transgenic plants produced herein are thus expected to be useful for a variety of commercial and research pu ⁇ oses.
- Transgenic plants can be created for use in traditional agriculture to possess traits beneficial to the grower (e.g., agronomic traits such as resistance to water deficit, pest resistance, herbicide resistance or increased yield), beneficial to the consumer ofthe grain harvested from the plant (e.g., improved nutritive content in human food or animal feed; increased vitamin, amino acid, and antioxidant content; the production of antibodies (passive immunization) and nutriceuticals), or beneficial to the food processor (e.g., improved processing traits).
- the plants are generally grown for the use of their grain in human or animal foods.
- root-specific promoters in transgenic plants can provide beneficial traits that are localized in the consumable (by animals and humans) roots of plants such as canots, parsnips, and beets.
- other parts ofthe plants including stalks, husks, vegetative parts, and the like, may also have utility, including use as part of animal silage or for ornamental pu ⁇ oses.
- chemical constituents e.g., oils or starches
- transgenic plants may be created which have enhanced or modified levels of such components.
- Transgenic plants may also find use in the commercial manufacture of proteins or other molecules, where the molecule of interest is extracted or purified from plant parts, seeds, and the like.
- Cells or tissue from the plants may also be cultured, grown in vitro, or fermented to manufacture such molecules.
- the transgenic plants may also be used in commercial breeding programs, or may be crossed or bred to plants of related crop species. Improvements encoded by the expression cassette may be transfened, e.g., from maize cells to cells of other species, e.g., by protoplast fusion.
- the transgenic plants may have many uses in research or breeding, including creation of new mutant plants through insertional mutagenesis, in order to identify beneficial mutants that might later be created by traditional mutation and selection.
- An example would be the introduction of a recombinant DNA sequence encoding a transposable element that may be used for generating genetic variation.
- the methods ofthe invention may also be used to create plants having unique "signature sequences" or other marker sequences which can be used to identify proprietary lines or varieties.
- the transgenic plants and seeds according to the invention can be used in plant breeding which aims at the development of plants with improved properties conferred by the expression cassette, such as tolerance of drought, disease, or other stresses.
- the various breeding steps are characterized by well-defined human intervention such as selecting the lines to be crossed, directing pollination ofthe parental lines, or selecting appropriate descendant plants. Depending on the desired properties different breeding measures are taken.
- the relevant techniques are well known in the art and include but are not limited to hybridization, inbreeding, backcross breeding, ultilane breeding, variety blend, interspecific hybridization, aneuploid techniques, etc.
- Hybridization techniques also include the sterilization of plants to yield male or female sterile plants by mechanical, chemical or biochemical means.
- transgenic seeds and plants according to the invention can be used for the breeding of improved plant lines which for example increase the effectiveness of conventional methods such as herbicide or pesticide treatment or allow to dispense with said methods due to their modified genetic properties.
- new crops with improved stress tolerance can be obtained which, due to their optimized genetic "equipment", yield harvested product of better quality than products which were not able to tolerate comparable adverse developmental conditions.
- the invention also provides a computer readable medium having stored thereon a data stracture containing nucleic acid sequences having at least 70% sequence identity to a nucleic acid sequence selected from those listed in SEQ ID Nos: 1-953, 2137-2661, 1954-1966, 2000- 2129, 2662-4737 and 4738-6813, as well as complementary, ortholog, and variant sequences thereof.
- Storage and use of nucleic acid sequences on a computer readable medium is well known in the art. (See for example U.S. Patent Nos. 6,023,659; 5,867,402; 5,795,716)
- nucleic acid sequences contained on the computer readable medium may be compared through use of a module that receives the sequence infonnation and compares it to other sequence information.
- a module that receives the sequence infonnation and compares it to other sequence information.
- other sequences to which the nucleic acid sequences ofthe invention may be compared include those maintained by the National Center for Biotechnology Information (NCBI)(http://www.ncbi.nlm.nih.gov/) and the Swiss Protein Data Bank.
- NCBI National Center for Biotechnology Information
- a computer is an example of such a module that can read and compare nucleic acid sequence information.
- the invention also provides the method of comparing a nucleic acid sequence ofthe invention to another sequence.
- a sequence ofthe invention may be submitted to the NCBI for a Blast search as described herein where the sequence is compared to sequence information contained within the NCBI database and a comparison is returned.
- the invention also provides nucleic acid sequence information in a computer readable medium that allows the encoded polypeptide to be optimized for a desired property. Examples of such properties include, but are not limited to, increased or decreased: thermal stability, chemical stability, hydrophylicity, hydrophobicity, and the like. Methods for the use of computers to model polypeptides and polynucleotides having altered activities are well known in the art and have been reviewed. (Lesyng et al., 1993; Surles et al., 1994; Koehl et al., 1996; Rossi et al., 2001). The invention will be further described by the following non-limiting examples.
- Example 1 Example 1
- RNA from plant tissue is extracted and quantified. 1. Quantify total RNA using GeneQuant
- Step 1 Primer hybridization: Incubate at 70 °C for 10 minutes
- RNA (10 ⁇ g final)-10 ⁇ l T7 (dT) 24 Primer (100 pmol fmal)-l ⁇ l pmol 5X 1st strand cDNA buffer-4 ⁇ l 0.1M DTT (10 mM final)- 2 ⁇ l 10 mM dNTP mix (500 ⁇ M final) -1 ⁇ l
- Image analysis and data mining Two text files are included in the analysis: a. One with Absolute analysis: giving the status of each gene, either absent or present in the samples b. The other with Comparison analysis: comparing gene expression levels between two samples
- R pathogen resistance
- RPS2 belongs to the NBS-LRR class of R genes, which can confer resistance to a wide variety of phytopathogens. It has been suggested that AvrRpt2 is delivered to the plant via the bacteria's type III secretion system and recognized by a surveillance system involving RPS2 inside the plant cell.
- the plant response during an incompatible interaction includes a change in ion flux across the plasma membrane, generation of reactive oxygen species, induction of defense genes, induction of HR, fortification ofthe cell wall, accumulation of salicylic acid, and anti-microbial compounds.
- differential gene expression is a classic and very powerful tool in experimental biology not only to study large trends in gene regulation but also small differences among similar responses. Historically, methods for analysis only allowed the comparison of a very few genes in each experiment. However, with new methods to identify and quantitate differential mRNA profiles, such as long distance differential display PCR, cDNA microarrays, and gene chips, one can much more quickly and comprehensively identify and analyze differentially expressed genes.
- By analyzing and comparing the expression profile of genes in the above 4-way matrix a number of types of genes can be identified that are involved in the resistance pathway. Resistance genes would be highly expressed or strongly downregulated in outcome number 2 in the four way matrix and less oppositely expressed in outcome numbers 1, 3, and 4.
- Genes that are highly expressed or strongly downregulated in outcome numbers 1 and 2 and oppositely expressed or not expressed above baseline in outcome numbers 3 and 4 are of interest as being associated with the reaction of a plant having resistance genes to a bacterial infection, regardless ofthe avr genot pe ofthe bacterium. Such a comparison is very useful in identifying strong candidates for different roles in plant/pathogen interactions, as are numerous other kinds of outcomes in the four- way plant/pathogen interaction analysis of gene expression.
- genes include those involved in recognition of pathogen (unrelated to virulence status); genes involved in recognition of pathogen having a virulence or avirulence gene (regardless ofthe status ofthe conesponding plant); genes related to the status ofthe plant, regardless ofthe status ofthe pathogen; and genes that do not change expression during plant-pathogen interaction.
- Isogenic strains of Arabidopsis thaliana ecotype Col-0 were used, one having the wild type RPS2 gene that confers resistance, and one having the mutant rps2 mutant that confers susceptibility to attack by Pseudomonas syringae pathovar tomato (Pst) carrying avrRpt2.
- RPS2 WT plant P. syringae (no avr) 2. RPS2 WT plant; P. syringae! avrRpt2
- Genes that fall within groups la and lb include genes directly involved in resistance to pathogens. These genes show a peak (either up or down) only during plant-pathogen interaction 2.
- the differential expression can be of two types: upregulated (increased expression of this gene is potentially important in the incompatible interaction) or downregulated (decreased expression of this gene is potentially important in the incompatible interaction).
- HSPs heat shock proteins
- HSFs Heat shock factors
- Eight HSF genes are known in Arabidopsis.
- HSF4 and HSF21 were identified as being upregulated when the plant was infected with P. syringae.
- HSF4 showed strong induction that was restricted to resistance, and HSF4 was the only HSF specifically upregulated during the incompatible interaction. The data suggests that the upregulation of HSPs is downstream of upregulation of HSF4.
- HSF4 was analysed in two different Arabidopsis ecotypes, A. thaliana, ecotypes Col-0 and Ws. HSF4 was also upregulated in the response of Ws ecotype to infection and, specifically, was upregulated during an incompatible response. HSF21 is thus a prefened protein for resistance applications, and HSF4, a protein which is expressed in all plants, is especially preferred for engineering resistance.
- a transgene containing the ACT2 promoter and the HSF4 open reading frame was introduced to Arabidopsis and transgenic HSF4 Arabidopsis lines generated to overexpress and underexpress HSF4.
- the expression of HSF4 during pathogen infection may cause lower general resistance to P. syringae.
- Conditional overexpression lines were also generated using the estradiol-inducible promoter system. Infiltration of 20 :M estradiol into the intercellular space ofthe leaves of transgenic plants induced expression of HSF4 mRNA for a short time (down by 4 hours). Addition of 20 estradiol to the hydroponic medium yielded sustained HSF4 mRNA accumulation.
- RNA samples were collected and used to prepare RNA. Three sets of experiments were carried out. Each set of experiments included three independent replicate experiments. RNA from replicate experiments was pooled to reduce enors arising from the effects of variations in environmental conditions. Each RNA sample was used to prepare a fluorescently-labelled probe which was applied to an Affymetrix GeneChipTM, allowing the expression level of each gene represented on the GeneChipTM to be determined for each sample.
- the plant genotypes included in each experiment were as follows:
- Expression values that were less than 5 were set to five. This ensures that no values are 0 or negative. Such values interfere with subsequent analysis steps.
- the ratios of infected wild-type to mock infected wild type were calculated for each experiment. Then genes were selected in which expression levels were infected wild-type/mock wild-type > 2.5, and infected wild-type > 50 for at least 2 of 3 experiments. The ratio of 2.5 was chosen because the false positive rate for the GeneChipTM is essentially 0 at this level of stringency, and the absolute value of 50 was chosen to eliminate expression values below the detection limit ofthe GeneChipTM.
- genes for which the ratio of infected mutant/infected wild-type was ⁇ 0.5 or > 2 for at least one mutant were selected from the list of 745 pathogen-inducible probe sets. The limits of 5 and 2 were chosen because changes of at least 2-fold are likely to be significant for impact on disease resistance, and because the false positive rate for the GeneChipTM at 2-fold is 0.2%. This selection yielded a list of 530 probe sets conesponding to genes, the expression of which is induced by Pseudomonas infection in wild-type plants and perturbed in at least one mutant plant (see Tables 4a and 4b below).
- genes comprising SEQ ID NOs:2, 4-6, 11-13, 18, 22-23, 28, 31, 36, 39-43, 45, 47, 49-50, 52, 54-55, 57-58, 60-61, 63-66, 71-72, 74, 77, 81, 83, 85, 87-89, 92, 97, 100-107, 111-112, 114-115, 117-120, 122, 125, 127-128, 134, 138-140, 143-144, 148-151, 153, 156-157, 160, 165, 168-170, 173-174, 176-180, 183, 187-188, 191, 193-194, 197-198, 200, 203-210, 214, 219-224, 227, 230-232, 235-23?, 239- 240, 243-246, 248-249, 251-254, 256-258, 261, 264, 266-268, 270, 272-275, 277-278
- Genes that encode regulatory proteins such as transcription factors, protein kinases, calcium binding proteins and the like, are likely to play important roles in disease resistance, as they are likely to affect the expression of multiple defense effector genes.
- the list of 530 probe sets include 81 that conespond to genes encoding regulatory factors. These are likely to be useful for engineering plants to respond more quickly to pathogen attack by activating expression of defense responses (see Table 5 below).
- genes comprising SEQ ID NOs:39, 52, 60, 63, 81, 83, 106, 107, 115, 117, 118, 168, 174, 176, 179, 204, 207, 208, 220, 221, 248, 258, 268, 275, 280, 309, 323, 326, 329, 351, 419, 422, 429, 430, 432, 459, 460, 468, 469, 473, 500, 505, 506, 508, 529, 531, 533, 535, 538, 545, 553, 602, 606, 608, 610, 614, 616, 634, 654, 655, 684, 686, 687, 691, 717, 751, 752, 766, 777, 815, 831, 834, 835, 839, 841, 847, 876, 884, 906, 920, and 924 is increased after infection of wild-type Arabidopsis, and altered after infection of at
- genes comprising SEQ ID NOs:12-13, 18, 23, 36, 39-40, 43, 45, 50, 52, 57-58, 60-61, 64, 71-72, 81, 87-89, 97, 100, 102-105, 107, 111-112, 115, 119-120, 122, 125, 127- 128, 140, 144, 148-150, 153, 165, 168-169, 176-177, 179, 183, 188, 191, 193-194, 197-198, 203-206, 208-209, 214, 219-222, 227, 230, 232, 237, 244-246, 248-249, 251-253, 258, 261, 264, 266, 268, 273-275, 283, 287, 290, 293, 297, 302, 305-306, 308, 312-315, 321-322, 324, 326, 330, 333, 338, 341, 345, 353, 356-358, 362-363
- Jasmonate and ethylene-dependent disease resistance responses are known to be important for resistance to the fungal pathogens Alternaria brassicicola and Botrytis cinerea, and may also be important for resistance to other necrotrophic fungal pathogens. Alternaria and Botrytis are distantly related, yet plant resistance to these fungi is controlled similarly, suggesting that jasmonate- and ethylene-dependent responses function to limit growth of a wide range of fungal pathogens. Consequently, pathogen-induced genes whose expression is reduced in coil and ein2 mutants are likely to be important for resistance to these necrotrophic fungal pathogens. These 296 probe sets are shown in Table 7 (see below).
- genes comprising SEQ ID NOs:2, 4, 6, 11-13, 18, 22-23, 31, 41-43, 49-50, 54, 57-58, 61, 64- 66, 71-72, 74, 77, 85, 87, 89, 92, 97, 101, 103, 106-107, 112, 114, 117-119, 125, 128, 134, 138, 143, 149, 151, 156-157, 165, 169-170, 174, 176-180, 187-188, 191, 193, 206, 208, 219- 220, 222, 224, 231, 236, 239, 243-245, 251-254, 256-257, 267, 272, 287, 290, 292, 297, 302, 312-313, 315-316, 321-322, 324-325, 328, 330, 345, 351, 353, 355-357, 362-363, 366, 368- 371, 373, 375,
- Such signaling is known to be important for resistance to the bacterial pathogen Pseudomonas syringae, the oomycete pathogen Peronospora parasitica, the viral pathogen tobacco mosaic viras, as well as various other plant pathogens. Consequently, pathogen-induced genes whose expression is reduced by one ofthe mutations that block salicylate signaling are likely to be important for disease resistance, and useful for engineering improved disease resistance.
- These 288 probesets are shown in Table 8 (see below).
- genes comprising SEQ ID NOs: 12-13, 18, 23, 36, 39-40, 43, 45, 50, 52, 57-58, 60-61, 64, 71-72, 81, 87-88, 100, 102-105, 107, 111-112, 115, 119-120, 122, 125, 127-128, 140, 148-150, 153, 168-169, 176-177, 188, 191, 193-194, 197-198, 203- 206, 209, 219-222, 227, 232, 237, 244-246, 248-249, 251-253, 258, 261, 264, 266, 268, 273- 275, 283, 287, 290, 293, 297, 302, 305-306, 308, 312-315, 324, 326, 330, 333, 341, 345, 353, 356, 358, 366, 371, 375, 377, 380, 385, 389, 392, 394, 398, 402-4
- Arabidopsis ecotypes Materials and Methods Arabidopsis ecotypes (or accessions) (the wild-types of all the Arabidopsis ecotypes used here have wild-type alleles of RPS2 and RPMI).
- Col Columbia-0 Ler, Landsberg erecta Ws, Wassilewskija Arabidopsis mutants and transgenics
- Col background Col background.
- NahG transgene for salicylic acid hydroxylase (inactivating salicylic acid).
- Col background. ndrl-1, null mutant allele of NDRI (non-race specific disease resistance).
- genes Four hundred sixty-five genes were specifically/preferentially induced in the incompatible interaction (WT and Pst/avrRpt2), and 616 genes were specifically/preferentially repressed in the incompatible interaction. Examples of these genes are provided in Tables 10 and 13. Gene expression patterns in the incompatible interaction in Col and Ws were significantly different, indicating that the genetic diversity among ecotypes can affect gene regulation during the incompatible interaction significantly. In comparison, a relatively small number of genes (314 genes for induction, 167 genes for repression) were affected at this thne point during the compatible interactions (but not preferential to the incompatible interactions).
- a comparison ofthe differences in the expression patterns ofthe 2 primary ecotypes of Arabidopsis ' ' response to infection provides a further way to identify which genes have a more universal role (unchanged expression pattern) and which may be very specific to a particular plant ecotype involved in a very specific gene-for-gene interaction. For example, responses that are common between two ecotypes may be important for resistance. Genes that show the same pattern in both ecotypes may be part of more universal, or commonly-used, mechanisms involved in plant-pathogen interactions. Responses that are different may indicate that the two ecotypes use different combinations of responses to achieve resistance. This implies that a variety of genes can participate in plant-pathogen interactions. Nevertheless, ecotype-specific responses are expected to have counte ⁇ arts in other plant species.
- the differences in resistance response between ecotypes can be used for improving resistance in plants.
- responses that are different between ecotypes using the methods and compounds ofthe invention, such a response can be added to (induced or repressed) the response seen in the ecotype which does not normally use that response. This will likely give the plant a more robust or a wider range of resistance.
- Table shows a comparison of gene expression in 4 ecotypes, i.e., Col-0, Ws-2, Cvi and Ler in response to infection.
- Table 10A shows the expression data for 9 probe sets conesponding to genes that are specifically induced at 3 hours after incompatible infection of four different ecotypes of Arabidopsis with P. syringae pv. tomato DC3000.
- Table 10B shows expression data for 18 probe sets conesponding to genes that are induced by 6 hours but not at 3 hours after incompatible infection of four different ecotypes of Arabidopsis with three different bacterial strains, i.e., P. syringae pv. tomato DC3000.
- Table IOC illustrates the expression data for 6 probe sets conesponding to genes that are activated by P. syringae at 6 hours post-infection. Most ofthe genes are compatible interaction-specific or -preferential.
- early inducible genes (3 hours) in the incompatible interaction were identified (70 genes are common in all the ecotypes, and 360 genes if selected for induced in at least one ecotype).
- One group ofthe early genes 38 genes in Col
- These genes did not respond in the compatible interaction at 3 hours and were repressed below the control level in the compatible interaction by 6 hours. This suggests that shutting down these genes in the incompatible interaction by 6 hours could be caused by defense response inhibiting factor(s) delivered by bacteria.
- Another group ofthe early genes were expressed even higher at 6 hours in the incompatible interaction.
- One hundred eighty-eight genes showed significant induction or repression at 3 hours in the compatible interaction in at least one ofthe ecotypes. Of these, 3 induced genes and 3 repressed genes were induced or repressed in all three ecotypes.
- ecotypes may use a different but overlapping set of responses to achieve resistance against the same pathogen.
- Gene expression profiling can thus reveal ecotype differences. Therefore, it is possible to isolate the genes responsible for these differences in regulatory mechanisms using ecotype differences in gene expression as a phenotype, by a map-based cloning approach.
- a majority ofthe incompatible response-inducible genes have lower basal levels in ecotype Ws and higher basal levels in ecotype Ler.
- the large differences in expression level constitute easy-to-score phenotypic markers.
- Ws and Ler are crossed to obtain F2 populations. The larger the F2 population is, the better resolution in the map position can be obtained.
- expression levels ofthe chosen phenotypic marker genes are measured and physical markers that distinguish these ecotype genomes are scored.
- the map position ofthe responsible gene is determined by analyzing the linkage between the phenotype and the physical markers.
- QTL quantitative trait locus
- the phenotype of interest in gene expression depends on bacterial infection, such as expression of ecotype Col-specific inducible genes at 6 hours after infection of Pst/avrRpt2, expression ofthe conesponding phenotypic marker genes (e.g., genes that show good difference in induction between Col and Ler) can be measured at an appropriate time after bacterial infection.
- expression of ecotype Col-specific inducible genes at 6 hours after infection of Pst/avrRpt2
- expression ofthe conesponding phenotypic marker genes e.g., genes that show good difference in induction between Col and Ler
- Preferred early inducible genes were selected as induced > 2.5 fold (except for 2 fold for Psp at 6 hours) in all ofthe following datasets: Pst/avrR ⁇ t2 at 3 hours in Col, Ws, and Ler; Pst/avrRpt2 at 3 hours, Psm/avrRpt2 at 3 hours, Psp at 6 hours, and Pst avrB at 3 hours, relative to the water control, as well as estradiol-inducible (avrRpml at 0, 45, and 120 minutes and avrRpt2 at 0, 45, and 120 minutes, where the fold change was relative to the appropriate resistance gene mutant carrying the same transgenes.
- genes were ranked according to genes that are not induced by S A or BTH and not induced in late time points with Psm. Regulatory genes were given higher rankings (see Table 11).
- the expression of genes comprising SEQ ID NOs:17, 70, 76, 81, 84, 109, 123, 144, 160, 230, 265, 268, 269, 271, 323, 333, 385, 427, 428, 430, 457, 505, 569, 597, 602, 606, 616, 708, 730, 741, 812, 862, and 942 is induced early after infection of different Arabidopsis ecotypes with Pseudomonas syringae pv tomato DC3000, P. maculicola ES4326 and P. phaseolica NPS3121 (at 3 or 6 hours) or is estradiol inducible (at 45 or 120 minutes).
- Prefened early repressible genes were selected as repressed > 2.5 fold (except for > 2 fold for Psp at 6 hours) in all ofthe following datasets: Pst/avrRpt2 at 3 hours, Psm/avrRpt2 at 3 hours, Psp at 6 hours, and Pst/avrB at 3hours) and Pst/avrRpt2 at 3 hours in Col (the fold change was relative to the appropriate water controls).
- the genes were ranked in order of expression (highest to lower levels of expression) (see Table 12).
- genes comprising SEQ ID NOs:30, 73, 282, 541, 640, 679, 761, 870, 917, and 930 is repressed early after infection of Arabidopsis with Pseudomonas syringae pv tomato DC3000, P. maculicola ES4326 and P. phaseolica NPS3121.
- genes are induced/repressed during incompatible interactions at 3 and/or 6 hours after inoculation of bacteria.
- Prefened genes in this group were selected as induced/repressed > 2.5 fold in the incompatible interaction compared to water inoculated control and 2 > fold compared to the conesponding compatible interaction at 3 and/or 6 hours after inoculation with Pst/avrRpt2 and Pst/avrB, and Psm/avrRpt2 and Pst/avrRpt2, in all four ecotypes (see Tables 13a and 13b).
- genes comprising SEQ ID NOs:21, 44, 46, 60, 86, 91, 93, 106, 110, 119, 122, 130, 131, 161, 166, 167, 168, 171, 176, 200, 203, 213, 225, 227, 248, 261, 262, 266, 274, 285, 300, 301, 302, 320, 326, 341, 345, 348, 349, 360, 366, 378, 615, 618, 406, 409, 422, 425, 441, 443, 446, 449, 454, 461, 475, 476, 485, 500, 511, 512, 527, 533, 543, 545, 549, 550, 552, 567, 575, 590, 608, 611, 625, 643, 656, 659, 666, 668, 671, 680, 690, 704, 706, 711, 721, 728, 738, 757, 791, 807, 811, 813
- genes comprising SEQ ID NOs:7, 33, 82, 136, 141, 154, 185, 189, 199, 202, 434, 471, 483, 499, 516, 530, 578, 586, 631, 658, 694, 714, 718, 734, 770, 772, 816, and 916 is decreased in an incompatible interaction at 3 and/or 6 hours after infection of four Arabidopsis ecotypes with Pseudomonas syringae pv tomato DC3000, P. maculicola ES4326 and P. phaseolica NPS3121.
- Garlic T-DNA insertion lines conesponding to these genes are searched by BLAST.
- Global expression profiling after infection with one of two different pathogens may be employed as a phenotyping method.
- Transgenic plants for overexpression, underexpression, and conditional overexpression of selected genes are also prepared.
- Genes were selected according to the conditions described below based on the results of a GeneChipTM analysis. These genes were particularly selected for a high level of induction in the avrRpt2-RPS2 interaction and for a very low mRNA level in the absence of pathogen attack among four Arabidopsis ecotypes tested (Col, Ws, Ler, and Cvi). The genes were also analyzed to determine if their expression was similar in other combinations of incompatible interactions (three different bacterial strain backgrounds: P. syringae pv. tomato DC3000, P. syringae pv. maculicola ES4326, and P. syringae p '.
- phaseolicola NP3121 phaseolicola NP3121; three different avirulence genes: avrRpt2, avrB, and avrRpml; and direct expression of avirulence genes in plants using an estradiol-inducible system).
- avrRpt2, avrB, and avrRpml direct expression of avirulence genes in plants using an estradiol-inducible system.
- the 1.2-kb sequence upstream of the initiation codon is provided in SEQ ID NOs: 1047-1095.
- Promoters were selected that had low basal expression level (i.e., uninduced level) in all the ecotypes (Col, Ler, Ws, and Cvi) and high inducibility in Col.
- Five such promoters of genes represented by the probe sets in Table 14 were identified: the promoters of germin precursor-like oxalate oxidase gene, extra-large G protein gene, PR-1, EREBP5 gene, and a C2H2-type zinc finger protein gene were chosen.
- the promoters for the germin-precursor like oxalate oxidase gene and PR-1 gene are relatively slow response promoters (no induction 3 hours after infection), but have high induction by 6 hours.
- the extralarge G protein gene is an intermediate in terms of response time, but maintains high expression over time.
- the other two are useful as early transient response promoters (good induction by 3 hours, but shut down by 6 hours) in the incompatible interaction (wild type plant infected with Pst/avrR ⁇ t2).
- Promoter sequences comprising SEQ ID NOs: 1046-1095 and 1047-1055 correspond to genes comprising one of SEQ ID Nos: 17, 21, 80, 81, 109, 156, 174, 176, 221, 227, 296, 302, 303, 306, 333, 340, 360, 500, 505, 524, 575, 601, 602, 614, 628, 687, 733, 782, 811, 835, 862, 900, 905, 912, and 109, 306, 524, 600, 875, 912, 913, 941 and 942, respectively.
- Promoter-LUC reporter fusions are prepared and tested in a transient expression system using biolistic co- bombardment of avrR ⁇ t2 gene. Promoters Responsive to Particular Pathogens
- Proteins that are useful for protecting plants from pathogen attack may have deleterious effects on plant growth if expressed constitutively. Consequently, it is desirable to have promoter sequences that control gene expression in such a way that expression is absent or very low in the absence of pathogens, and high in the presence of pathogens.
- Wild-type Arabidopsis plants (ecotype Columbia) were either mock-infected or infected with the bacterial pathogen Pseudomonas syringae pv. maculiola strain ES4326 (2 x 10 cfu per square centimeter of leaf). After 30 hours, samples were collected, and RNA was purified. This procedure was repeated three times independently, and the RNAs from conesponding samples were pooled, in order to reduce the impact of variation due to uncontrolled variables. The two pools of RNA representing mock-infected and infected plants were then used for gene expression profiling using an Arabidopsis GeneChip ® . This entire procedure was repeated three times, yielding three sets of GeneChip data representing a total of nine independent experiments.
- genes were selected whose expression level was less than 40 in all ofthe mock-infected samples and whose expression level was greater than 400 in all ofthe infected samples.
- the value of 40 was chosen arbitrarily as a low expression level and the value of 400 was chosen arbitrarily as a reasonably high expression level.
- Thirty-seven genes met these criteria and promoter sequences could be identified for 36 of them.
- Table 15 indicates the identifying probe set number for these 36 genes, the conesponding Arabidopsis gene, the mean expression level of each gene in mock-infected plants, the mean expression level of each gene in infected plants, and the fold induction in expression of each gene after infection.
- genes comprising SEQ ID NOs: 104-106, 119, 123, 129, 131, 151-152, 183, 191, 198, 200, 227, 249, 274, 302, 358, 415, 481, 547, 566, 582, 628, 633, 639, 656, 673, 793, 818, 827, 864, 874, 880, and 904-905 is induced in Pseudomonas syringae pv. ⁇ ew/.o/ ⁇ -infected Arabidopsis.
- promoters that strongly activate gene expression in response to infection by a bacterial pathogen might be different from promoters that strongly activate gene expression in response to infection by a fungal pathogen.
- a second GeneChip ® experiment was conducted, in which wild-type Arabidopsis plants (ecotype
- genes were selected whose expression level was less than 40 in mock-infected samples from all time points and whose expression level was greater than 400 in infected plants at 84 hours after infection. Twenty-three genes met these criteria, and promoter sequences could be identified for 21 of them.
- genes are described in Table 16, with their identifying probe set number, the conesponding Arabidopsis gene, the mean expression level of each gene in mock- infected plants, and the expression level of each gene in infected plants at various times after infection.
- 11 genes were previously identified in the search for genes whose expression was strongly induced by Pseudomonas syringae infection. These 11 genes conespond to identifying codes 12989, 13015, 13100, 13215, 13565, 14609, 16649, 16914, 19284, 19991, and 20356.
- genes comprising SEQ ID NOs:18, 71, 119, 123, 129, 151, 191, 244, 245, 302, 545, 547, 562, 566, 637, 653, 747, 756, 774, 793, 842, 864, and 905 is induced in Botrytis cinerea-mfected Arabidopsis.
- the promoter sequences for the 25 genes that were only identified in the P. syringae data set are shown in SEQ ID NOs:1001-1025.
- the promoter sequences for the 10 genes that were only identified in the P. cinerea data set are listed in SEQ ID NOs: 1026-1035)
- the promoter sequences ofthe 11 genes that were identified in both data sets are listed in SEQ ID NOs: 1036-1046.
- the 11 promoter sequences that were identified in both data sets are most likely to be useful for driving expression of transgenes in response to attacks by various pathogens, as these promoters are activated in response to attack by either Pseudomonas syringae or Botrytis cinerea, two very different pathogens.
- the other promoters may also be useful for driving expression of transgenes that are efficiently expressed in response to infection by certain types of pathogens.
- orthologs of the Arabidopsis promoters are also useful to drive expression of transgenes.
- a BLAST search for orthologous genes was conducted.
- the alignments from the BLAST search are used to determine the range of nucleotides showing homology to the Arabidopsis gene.
- the coding sequences shown at the beginning of each search result that contain regions conesponding to the nucleotides showing homology are likely orthologous genes.
- Orthologous promoter sequences may be isolated by any method known to the art, e.g., cloning of genomic DNA 5' to the ATG in orthologous genes identified in a computer assisted database search or hybridization of a probe comprising any one of SEQ ID NOs: 1001-1046 to genomic plant DNA.
- Example 6
- the host genes may include host factors that are induced by viral infection, e.g., activated host defense genes, suppressed by viral infection, e.g., suppressed host defense genes, genes involved in symptom development, as well as genes regulated by virus inducible promoters. Once the genes are identified, the function of each is then determined. Reverse genetics is then employed to examine the effect of mutations on these genes during virus infection.
- Arabidopsis thaliana (Colurnbia-0 (Col-0) were grown in a Conviron growth chamber to 4 weeks of age. The growth conditions were 22°C, 12 hour day length and 75% relative humidity. At least four rosette leaves of twenty plants were inoculated with one of five viruses or a mock control (120 plants total).
- the viruses were turnip vein clearing viras (TVCV), a tobamoviras, an oil seed rape mosaic virus (ORMV), a tobamoviras, tobacco rattle tobraviras (TRV), a tobraviras, cucumber mosaic viras strain Y (CMV-Y), a cucumoviras, and turnip mosaic viras (TuMV), a potyvirus.
- Each viras was diluted to approximately 0.5 to 1.0 ⁇ g/ml in 10 mM potassium phosphate buffer pH 7.2 (or 20 mM Tris-HCI pH 8.0 for the TuMV). The phosphate buffer was used as the mock infection control for the experiments.
- Inoculated Col-0 leaves were first dusted with carborundum then 10 ⁇ l of virus solution or phosphate buffer were pipetted onto the leaf surface. The viras solution or phosphate buffer alone were then rubbed into the leaf surface using a gloved finger, and the leaf surfaces were washed with distilled water at about 10 minutes post inoculation.
- Arabidopsis genes The hybridization data was then analyzed using Affymetrix GeneChip software. Arabidopsis genes that were induced by at least 2-fold in all virus treatments were identified by importing the data into Microsoft Excel and then subjecting the data to selection criteria. Within each time point, the expression level of a gene exceeded 25 and the fold change was greater than 2 by comparison with the mock-infected treatment. Thus, for genes that were induced by all five viruses, the expression level exceeded 25 and the fold change was greater than 2 for all five virases. For genes that were repressed by at least 2-fold, the expression level ofthe gene must exceed 25 in the mock-infected treatment and the fold change must be less than 2 in all ofthe five viras treatments. Results A gene chip from Affymetrix having oligonucleotides conesponding to approximately
- Arabidopsis genes was used with labeled cRNA obtained from plant cells infected with a selected viruses at different days post-infection (dpi).
- the RNA may be obtained from Arabidopsis infected with potyvirus, tobamoviras, tobraviras, cucumoviras or geminivirus.
- laser scanning is employed to detect expression levels and the data obtained is then analyzed. For genes that are induced in response to viral infection, genes that are expressed at levels greater than, for example, 2 fold over control, are selected. Alternatively, for genes that are suppressed in response to viral infection, genes that are expressed at levels lower than control are selected.
- a gene chip in such an analysis includes a global gene expression analysis, quantitative results, a highly reproducible system, and a higher sensitivity than Northern blot analyses.
- a gene chip with Arabidopsis DNA has a further advantage in that the Arabidopsis genome is well characterized.
- the HR (hypersensitive resistance) system of Chenopodium spp. is attractive because ofthe broad-spectrum virus resistance it confers. This is shown by the ability of members ofthe bromo-, como-, cucumo-, ilar-, alfamo-, nepo-, sobemo-, tombus-, tymo-, carla-, clostero-, hordei-, potex-, poty-, tobra- and tobamoviras groups to elicit local lesion HR on Chenopodium spp. (CMI/AAB Description of Plant Virases, 1984; Cooper et al., (1995)). In many instances, the HR completely blocks viral spread. However, certain virases can break through the hypersensitive response and move from one species of Chenopodium to another. The ability of some viruses to infect more than one species of Chenopodium provides an opportunity to isolate genes that provide a cell with resistance to viral infection.
- Chenopodium spp. HR The genetic mechanisms of Chenopodium spp. HR involve a number of factors. These factors can be studied to further understand the hypersensitive response and the mechanism through which the response acts. There are some similarities between the products of Chenopodium spp. genes and gene products involved in common defense signaling pathways in other plants. These similarities allow comparisons to be made between Chenopodium and these other plants.
- One example includes genes that are induced upon viral infection during HR in C.foetidum (Visedo et al., (1990). Additionally, some circumstantial experimental evidence suggests that Chenopodium HR may be somewhat similar to tobacco N gene HR (Whitham et al., 1994).
- TMV tobacco mosaic tobamoviras
- TMV will not induce HR cell death in ⁇ tobacco protoplasts where plasmodesmata are not intact (Otsuki et al., 1972), although HR does occur in callus cultures where plasmodesmata are intact (Beachy and Murakishi, 1971).
- BMV movement defective brome mosaic bromovirus
- C. amaranticolor cucumber mosaic cucumoviras (CMV) lacking a movement protein replicates within inoculated cells, fails to move and does not elicit cell death (Canto and Palukaitis, 1999). Therefore, like TMV on N gene tobacco, the process of viral spread of BMV and CMV in C. quinoa and C. amaranticolor may induce HR.
- TMV-MGfus Leaves of 10-week old C. amaranticolor or C. quinoa were inoculated with in vitro transcripts of TMV-MGfus (Heinlein et al, 1995), TMV virions, tobacco rattle tobraviras (TRV), or they were mock-inoculated.
- TMV-MGfus encodes GFP (green fluorescent protein) fused to the viral movement protein. Infectious spread can be monitored through the detection of GFP.
- GFP green fluorescent protein
- Leaves inoculated with TRV or TMV were collected at 4 dai, at which point local lesions were forming. Mock-inoculated tissue was collected at the same time. Tissue was frozen in liquid nitrogen and total R ⁇ A was purified from it. Three separate sets of plants were inoculated with TMV-MGfus and yielded three independent preparations of R ⁇ A.
- cD ⁇ A-AFLP complementary D ⁇ A-amplified fragment length polymo ⁇ hism
- Poly-A+ RNA was isolated from TMV-MGfus infected C.
- cDNA was generated using cDNA synthesis reagents from Life Technologies (RockviUe, MD). cDNA was used to generate AFLP fragments with the AFLP reagents from Life Technologies and reactions were performed according to the manufacturer's instructions. cDNA made from one microgram of poly- A+ RNA was digested with EcoRI and Msel and the supplied compatible linkers were ligated to the ends ofthe digested molecules. A few modifications were introduced.
- EcoRI-NN primers (GACTGCGTACCAATTCNN; SEQ ID NO:2134), rather than EcoRI-NNN, were used with the 5' fluorescent label NED (Applied Biosystems, Foster City, CA) and Msel-N and Msel-NN [GATGAGTCCTGAGTAAN(N); SEQ ID NO:2135), rather than Msel-NNN, primers were used (Genosys, The Woodlands, TX), to reduce the complexity ofthe primer sets evaluated.
- AU possible primer combinations (256 + 64) were used for PCR amplification and products were separated on polyacrylamide gels and visualized using a Genomyx SC fluorescent scanner (Beckman Coulter, Fullerton, CA).
- DNase treated total RNA (2 ng per reaction) from the third independent preparation of TMV-MGfus infected C amaranticolor, the first preparation of TRV infected C. amaranticolor, or the first preparation of TMV C. quinoa was used with TaqMan One-Step RT-PCR reagents for quantitative analysis in an ABI 7700 (Applied Biosystems). Reactions were performed according to the manufacturer's instructions. Primers and 6-FAM 5' end- labeled probes (6-carboxyfluorescein, Applied Biosystems or Genosys) were designed from the sequences from the C.
- HR is the end result of disease activated signaling events.
- C. amaranticolor was infected with RNA transcripts of TMV- MGfus that express GFP (green fluorescent protein) in infected cells. This allowed the spread of viral infection to be monitored over time. Infection foci comprising over 100 cells could be detected at 4 dai and foci of more than 500 cells could be detected at 7 dai.
- DESCA1 The expression level of DESCA1 increased the most in the TMV-MGfus infected plants.
- the expression level of DESCA1 increased 200 times by 4 dai but tapered off drastically by 11 dai.
- DESCA1 is unrelated to any protein known at this time.
- DESCA4 and DESCA10 Two sequences, DESCA4 and DESCA10, are both related to pumps found in Arabidopsis and yeast (Sanchez-Fernandez et al., 1998; Smart and Fleming, 1996).
- DESCA4 is expressed highly at 4 dai but the expression drops off over time whereas DESCAl 0 is only moderately induced and its expression returns to normal by the time ofthe visible appearance of local lesions in C. amaranticolor.
- DESCA7 is similar to a salicylate-induced glucosyltransferase gene in tobacco (Horvath and Chua, 1996).
- DESCA9 is similar to cytochrome P450-like proteins which can produce cytotoxic compounds including phytoalexins that are deployed by a plant to defend against invading microbes.
- DESCA12 is related to a proanthranilate benzoyltransferase from carnation that plays a direct role in the phytoalexin biosynthesis in carnation (Yang et al., 1998).
- DESCAl 1 is similar to the tryptophan biosynthetic enzyme phosphoribosylanthranilate transferase whose gene expression is induced in the presence of ozone in Arabidopsis (Conklin and Last, 1995).
- DES C A3 is similar to endo-l,4-betaglucanases that have a role in fruit ripening, abscission, and cell elongation (Lashbrook et al., 1994). DESCA3 is highly expressed in the infected C. amaranticolor and remains highly expressed during the appearance of local lesions and necrosis.
- DESCA5 is loosely similar to a yeast potential transcriptional regulator. DESCA5 expression is twice as high at the early stages of infection compared to the late stages of infection illustrating an important role played by gene regulation at the early stages of infection.
- DESCA6 is related to kinases of Arabidopsis. Kinases have essential roles in programmed cell death during viral infection (Dunigan and Madlener, 1995).
- DESCA2 is the most highly expressed ofthe group suggesting that it is an important regulator at the onset of infection. It is similar to a receptor-like protein kinase in bean that responds to Fusarium solani attack (Lange et al., 1999).
- R genes have kinase-like regions that may function in initiating a signal cascade during the onset of HR (Song et al.; 1995, Zhou et al., 1997).
- Global amino acid sequence alignment (Henikoff and Henikoff, 1992) of DESCA2 with Pto or Xa21, R genes with ser/thr kinase domains, reveals a 37% similarity.
- DESCA8 has a nucleotide binding site and a leucine-rich repeat that is common for many R genes. (Meyers et al., 1999; Leister et al., 1998).
- DESCA gene expression levels in infected tissue were compared to mock inoculated tissue by quantitative RT-PCR and revealed that the same DESCA genes upregulated during a TMV infection are also upregulated during a TRV infection (Table 20b). The gene expression levels in TMV infected C. quinoa were measured using the same
- DESCAl 2 and DESCA9 are respectively similar to hypersensitivity related gene 201, possibly a proanthranilate benzoyltranferase, and p450 monooxygenases, both which are expressed during the hypersensitive response in tobacco upon infection with Pseudomonas solanacearum but are not regulated by SA (Czernic et al., 1996).
- DESCA7 is similar to a salicylate-induced glucosyltransferase gene in tobacco (Horvath and Chua, 1996).
- the disease resistance response in C. amaranticolor involves pathways both dependent and independent of SA signaling.
- the activation phase involves cytochrome P450 monooxygenases introducing functional groups (e.g. aromatic rings) to potential toxins.
- the conjugation phase in plants involves the linking of glutathione or glucose to the toxin at which point the conjugated molecule can be recognized by an ATP-binding cassette transporter and pumped into the vacuole, or possibly the neighboring cells, during the elimination phase.
- the final phase includes either storage or breakdown of such molecules.
- DESCA9 similar to cytochrome P450
- DESCA12 similar to a gene associated with the production of phytoalexin
- C. amaranticolor produces many such compounds that are antiviral to TMV.
- DESCA7 similar to a glucosyltransferase, may conjugate such toxins to be transported by the ABC- transporters encoded by DESCA4 or DESCA10.
- the transported compound could then be deployed by the infected plant cell as an antiviral agent or cytotoxic compound, stored by noninfected cells in anticipation of infection, or eliminated by noninfected cells neighboring infected cells. Since all of these genes are induced by TMV and TRV in C. amaranticolor, their induced expressions are a result of a specific or general multivirus or disease resistance pathway.
- DESCA8 Two genes that may be used for early recognition of viral infection are DESCA8 and DESCA2, as these genes may act as signaling components to initiate the resistance cascade.
- DESCA8 has a nucleotide binding site and a leucine-rich repeat that is common for many R genes and that can be found in other plants (Meyers et al., 1999; Leister et al., 1998).
- DESCA2 is induced in both Chenopodium species and is similar to other R genes, Xa21 and Pto, which have similar ser/thr kinase domains.
- Resistance to viral spread may be transfened between Chenopodium spp.
- BMV bromine mosaic virus
- the systematic spread ofthe BMV virus may be restricted in the green variety of C. hybridum by transformation with a gene from the pu ⁇ le variety that does limit spread ( Komari, 1990).
- genes that confer viral resistance may be used for complementation, reverse genetics, overexpression, and gene silencing.
- the Chenopodium genes may function to initiate hj ⁇ ersensitivity in crops, Arabidopsis or other useful plants.
- Plant-Pathogen Interactions The methods set out hereinabove can be used for any type of comparable resistance interaction.
- any ofthe following plant/pathogen interactions will be produced as compatible and incompatible interactions.
- the RNA from such an interaction is isolated and subject to a protocol such as one outlined in Example 1, e.g., using a Genechip with a specific plant's genes or microanay, differential display PCR or cDNA-ALFP (Example 7). A four- way analysis is performed and genes which are expressed differently are identified.
- the plant/pathogen interactions in Table 21 are well known in the art. However, any type of plant/pathogen interaction that involves this type of resistance can be used.
- Genes that are upregulated and cause resistance in a wide variety of plants are particularly useful in methods which upregulate or overexpress the gene.
- One method is to add an exogenous copy, thus providing more ofthe gene product or allowing for a different induction from that used by the plant.
- the endogenous gene can be upregulated using a known inducer or using artificial methods such as using an artificial induction signal in the endogenous promoter. Examples ofthe two methods are provided in Examples 9 and 10.
- embodiments ofthe invention provide the sequences disclosed herein, which sequences can be used in genetic engineering of crops, as probes and markers to study the dynamics of plant/pathogen interactions, and as markers in marker-assisted breeding protocols to identify plants carrying particularly useful combinations of genes associated with pathogen resistance, as well as in plant defense.
- resistance genes such as those identified herein can be introduced into plant cells to generate transgenic plants having enhanced resistance.
- HSF4 is any prefened gene for this embodiment ofthe invention
- the invention can be employed with other genes, alone or in combination, whose regulation is strongly responsive to plant/pathogen interactions, such as the genes identified herein. Since some genes are strongly induced and others are strongly repressed in plant/pathogen interactions, and since some genes that are strongly induced in one ecotype can be strongly repressed in another, the invention contemplates use of any ofthe genes and sequences, or fragments thereof, disclosed herein, in a construct adapted to cause overexpression, repression, or knock out, ofthe genes in a transgenic plant.
- Transgenic downregulation of genes associated with pathogen resistance can have several useful applications.
- transgenic downregulation of genes that are strongly repressed in resistance interactions can enhance resistance.
- Such transgenic downregulation can employ the genes disclosed herein, or fragments thereof, in an antisense orientation to interfere with accumulation ofthe products of those genes.
- any other methodology capable of lowering expression of such genes is also included within these embodiments ofthe invention.
- Plant transformation can be canied out by conventional means, and can include
- Transfonned plant cell are then used to regenerate one or more plants in tissue culture. Subsequent generations of transgenic plants can be used directly or bred with other lines to generate plants having enhanced pathogen resistance.
- embodiments ofthe invention usefully employ the genes disclosed herein, or fragments thereof, for screening to identify useful chemical inducers and/or repressors of gene responsive to pathogenic infections.
- the method relies on the fact that a protein contains domains which can be separated.
- the protein of interest is fused to the GAL4 DNA binding region of a known protein.
- the GAL4 (or another) activation signal is fused in a library to produce a library of fused proteins. If one ofthe proteins from the library interacts with the protein of interest the protein binds and a signal protein is produced, such as luciferase.
- cDNA from HSF4 and any other protein of interest is cloned in fusion to the yeast GAL4 DNA binding domain on a vector.
- a library containing cDNA from Arabidopsis is fused to the GAL4 or an activation domain of choice. Expression of luciferase conelates with identification of an interacting protein. This protein is then analyzed as to its action as an inducer or repressor.
- a promoter sequence as given in SEQ ID Nos: 2137-2661 and 4738-6813 preferably a promoter sequence of one ofthe genes defined by SEQ ID Nos 536-579 such as SEQ ID Nos: 536; 537; 539-542; 548; 550-553; 555-558; 560; 565-568; 571-576, 578 and 579, or a promoter ortholog thereof is fused to the ⁇ -glucuronidase (GUS) gene at the native ATG to obtain a chimeric gene cloned into plasmid DNA.
- GUS ⁇ -glucuronidase
- the plasmid DNA is then digested with restriction enzymes to release a fragment comprising the full-length promoter sequence and the GUS gene, which is then used to constract the binary vector.
- This binary vector is transformed into Agrobacterium tumefaciens, which is in turn used to transform Arabidopsis plants.
- the above plasmid can also be used to form a series of 5' end deletion mutants having increasingly shorter promoter fragments fused to the GUS gene at the native ATG.
- Various restriction enzymes are used to digest the plasmid DNA to obtain the binary vectors with different lengths of promoter fragments.
- a binary vector 1 is constructed with a 1,900-bp long promoter fragment; a binary vector 2 is constructed with a 1,300-bp long promoter fragment; a binary vector 3 is constracted with a 1000-bp long promoter fragment; a binary vector 4 is constructed with a 800-bp long promoter fragment; a binary vector 5 is constructed with a 700-bp long promoter fragment; a binary vector 6 is constracted with a 600-bp long promoter fragment; a binary vector 6 is constracted with a
- these 5' end deletion mutants are also transformed into Agrobacterium tumefaciens and, in turn, Arabidopsis plants (for further details of Arbabidopsis transformation and promoter assay procedures see example 5 above) .
- Minimal promoter fragments having lengths substantially less than the full-length promoter can therefore be operatively linked to coding sequences to form smaller constructs than can be formed using the full-length promoter.
- shorter DNA fragments are often more amenable to manipulation than longer fragments.
- the chimeric gene constructs thus formed can then be transformed into hosts such as crop plants to enable at- will regulation of coding sequences in the hosts.
- linker-scanning mutagenesis allows for the identification of short defined motifs whose mutation alters the promoter activity. Accordingly, a set of linker- scanning mutant promoters fused to the coding sequence ofthe GUS reporter gene are constructed.
- Each of them contains a 8-10-bp mutation located between defined positions and included in a promoter fragment as given in SEQ ID Nos: 2137-2661 and 4738-6813, preferably a promoter sequence of one ofthe genes defined by SEQ ID NOs 536-579 such as SEQ ID Nos: 536; 537; 539-542; 548; 550-553; 555-558; 560; 565-568; 571-576, 578 and 579 or the promoter orthologs thereof.
- SEQ ID Nos 536-579 such as SEQ ID Nos: 536; 537; 539-542; 548; 550-553; 555-558; 560; 565-568; 571-576, 578 and 579 or the promoter orthologs thereof.
- Each constract is transformed into Arabidopsis and GUS activity is assayed for 19 to 30 independent transgenic lines.
- the presenceof the conect hybrid consstract in transgenic lines is confirmed by PCR amplification of all lines containing the mutant constracts and by random sampling of lines containing the other constructs.
- Amplified fragments are digested with restriction enzyme (e.g.Xbal) and separated on high resolution agarose gels to distinguish between the different mutant constracts. constracts.
- restriction enzyme e.g.Xbal
- the effect of each mutation on promoter activity is compared to an equivalent number of transgenic lines containing the unmutated constract. Two repetitions resulting from independent plating of seeds are canied out in every case.
- the sequences mutated in the linker-scanning constracts in particular those that showed marked differences from the control constract, are then examined more closely.
- BLAST database was created that was a subset of GenBank ver 123.0 (released April 15, 2001) that contained all ofthe plant translated regions excluding Arabidopsis thaliana sequences. The subset was created with PERL script. A BLAST search with all ofthe peptide sequences was performed against the GenBank subset. Each query was executed using the "blastall" command with the parameters" "-p blastp", “-v 50", “-b 50", "-F F".
- the candidate orthologs were further filtered by comparing words in the description to the text ofthe annotation fields: product, function and note. The sequence was considered to have the same or similar function if any ofthe words matched. Words excluded from the filter included: the, like, protein, related, unknown, subunit, hypothetical, and, putative, precursor, clone, homolog, small, beta, class, dna, rna, alpha, gamma, has, not, been, from, to, by, long, type and induced.
- amino acid sequences were used that resulted from FGENESH
- T microtubule-associated protein [Arabidopsis thaliana]
- Table 4a Probe Sets in addition to those in Table 4b corresponding to genes, the expression of which is induced by Pseudomonas infection in wild-type Arabidopsis plants and perturbed in at least one mutant plant
- Table 4b Probe Sets as referred to in Table 3 corresponding to genes, the expression of which is induced by Pseudomonas infection in wild-type Arabidopsis plants and perturbed in at least one mutant plant
- 12905_s_at (ATERF2_S_AT) 12911 .
- _s_at (ATG6PDHE5_S__AT)
- 17128_s_at (ATHRPRP1A_S_AT) 17180. _at (AF007270.30_AT) 17187_at (AF128396.2_AT) 17300_at (X66017.2_AT) 17303_s_at (AC004683.25_S_AT) 17323__at (U95973.69_AT) 17338_at (AC002535.97_AT) 17341_at (AL021713.89_AT) 17356_s_at (Z97338.190__S_ .
- Table 5 Probe Sets as referred to in Tables 4a and 4b corresponding to genes encoding regulatory proteins, the expression of which is increased after infection of wild- type Arabidopsis, and altered after infection of at least one mutant Arabidopsis, with Pseudomonas syringae
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WO2001007603A1 (en) * | 1999-07-22 | 2001-02-01 | Auburn University | Cloning of nps45: a gene encoding a putative translation initiation/stabilization factor |
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CN110157690A (zh) * | 2019-05-14 | 2019-08-23 | 中国农业科学院植物保护研究所 | 飞蝗过氧化物还原酶及其编码基因与应用 |
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