WO2011019331A1 - Methods for enhancing the production and consumer traits of plants - Google Patents

Methods for enhancing the production and consumer traits of plants Download PDF

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Publication number
WO2011019331A1
WO2011019331A1 PCT/US2009/004623 US2009004623W WO2011019331A1 WO 2011019331 A1 WO2011019331 A1 WO 2011019331A1 US 2009004623 W US2009004623 W US 2009004623W WO 2011019331 A1 WO2011019331 A1 WO 2011019331A1
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Prior art keywords
plant
shrunken
seed
mutant
comparison
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PCT/US2009/004623
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English (en)
French (fr)
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Bryant Jerome Long
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Abbott & Cobb, Inc.
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Priority to EP09848319A priority Critical patent/EP2464215A4/en
Priority to NZ597801A priority patent/NZ597801A/en
Priority to BRBR112012003137-6A priority patent/BR112012003137A2/pt
Priority to PCT/US2009/004623 priority patent/WO2011019331A1/en
Priority to MX2012001647A priority patent/MX2012001647A/es
Priority to AU2009351092A priority patent/AU2009351092B2/en
Priority to CA2769182A priority patent/CA2769182C/en
Priority to JP2011545328A priority patent/JP5727384B2/ja
Priority to JP2011545382A priority patent/JP2012516136A/ja
Priority to CA2769183A priority patent/CA2769183C/en
Priority to NZ597802A priority patent/NZ597802A/en
Priority to AU2010282964A priority patent/AU2010282964B2/en
Priority to MX2012001648A priority patent/MX2012001648A/es
Priority to NZ629020A priority patent/NZ629020A/en
Priority to EP10808453A priority patent/EP2464213A4/en
Priority to BR112012003139-2A priority patent/BR112012003139B1/pt
Priority to PCT/US2010/002212 priority patent/WO2011019391A1/en
Publication of WO2011019331A1 publication Critical patent/WO2011019331A1/en
Priority to ZA2012/00404A priority patent/ZA201200404B/en
Priority to IL217990A priority patent/IL217990A/en
Priority to IL217991A priority patent/IL217991A/en
Priority to CL2012000344A priority patent/CL2012000344A1/es
Priority to CL2012000345A priority patent/CL2012000345A1/es
Priority to JP2014224593A priority patent/JP5875661B2/ja
Priority to ZA2015/06352A priority patent/ZA201506352B/en
Priority to IL241095A priority patent/IL241095A0/en

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Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
    • A01H1/00—Processes for modifying genotypes ; Plants characterised by associated natural traits
    • A01H1/10—Processes for modifying non-agronomic quality output traits, e.g. for industrial processing; Value added, non-agronomic traits
    • A01H1/101—Processes for modifying non-agronomic quality output traits, e.g. for industrial processing; Value added, non-agronomic traits involving biosynthetic or metabolic pathways, i.e. metabolic engineering, e.g. nicotine or caffeine
    • A01H1/102—Processes for modifying non-agronomic quality output traits, e.g. for industrial processing; Value added, non-agronomic traits involving biosynthetic or metabolic pathways, i.e. metabolic engineering, e.g. nicotine or caffeine involving modified carbohydrate or sugar alcohol metabolism, e.g. starch biosynthesis
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
    • A01H1/00—Processes for modifying genotypes ; Plants characterised by associated natural traits
    • A01H1/04—Processes of selection involving genotypic or phenotypic markers; Methods of using phenotypic markers for selection
    • A01H1/045—Processes of selection involving genotypic or phenotypic markers; Methods of using phenotypic markers for selection using molecular markers
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
    • A01H5/00—Angiosperms, i.e. flowering plants, characterised by their plant parts; Angiosperms characterised otherwise than by their botanic taxonomy
    • A01H5/10—Seeds
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01H—NEW PLANTS OR NON-TRANSGENIC PROCESSES FOR OBTAINING THEM; PLANT REPRODUCTION BY TISSUE CULTURE TECHNIQUES
    • A01H6/00—Angiosperms, i.e. flowering plants, characterised by their botanic taxonomy
    • A01H6/46—Gramineae or Poaceae, e.g. ryegrass, rice, wheat or maize
    • A01H6/4684—Zea mays [maize]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
    • Y02P60/80—Food processing, e.g. use of renewable energies or variable speed drives in handling, conveying or stacking
    • Y02P60/87—Re-use of by-products of food processing for fodder production

Definitions

  • the present invention is directed to unique methods for producing plants, plant materials and seeds that very advantageously have enhanced production and consumer traits, such as an improved vigor and hardiness of the seeds, seedling emergence and plant growth, combined with a superior taste quality, and to improved plants, plant materials and seeds that are produced in accordance with these methods, or that have such traits.
  • Corn is one of the most diverse grain crops that is present in nature, and there are a number of different types of corn, which are generally classified by characteristics of their kernel endosperm.
  • the most common types of corn include flint, flour, dent, pop, sweet, waxy and pod.
  • the physical appearance of each kernel type is determined by its endosperm pattern, quality and quantity.
  • Sweet corn is a kind of corn plant that is classified as Zea mays, var. rugosa, and that has white, yellow or bi-colored kernels that are sweet when they are in the immature milky stage as a result of having a high sugar content. Higher levels of sugar in the sweet corn kernels result in a lower osmotic potential, causing greater water uptake into the kernels. Sweet corn is typically eaten by human beings as a vegetable, either directly from the maize cob, or by having the sweet kernels removed from the cob, and is a major vegetable crop that is grown all over the world primarily for fresh consumption, rather than as animal feed or for flour production.
  • Sweet corn occurs as a spontaneous mutation in field corn, and can be the result of naturally-occurring mutations in the genes that control conversion of sugar to starch inside the endosperm of the corn kernel.
  • sweet corn is typically picked when it is immature (at the milk stage), and eaten as a vegetable, rather than as a grain.
  • sweet corn typically stores poorly, and must be eaten in a fresh, canned or frozen manner before the kernels become tough and/or starchy. Following harvest, or if left on the stalk too long, sucrose in standard sweet corn becomes rapidly converted to starch. Kernels can lose as much as 50% of their sucrose at room temperature at around 24 hours after harvest.
  • the fruit of the sweet corn plant is the corn kernel, and the ear consists of a collection of kernels on the cob. Because corn is a monocot, there is always an even number of rows of kernels. The ear is covered by tightly wrapped leaves (the husk). Sweet corn has significant antioxidant activity, which can reduce the possibilities of developing heart disease and/or cancer. It also releases increased levels of ferulic acid, which provides additional health benefits.
  • Varieties of sweet corn that contain the shrunken-2 (sh2) gene typically produce higher than normal levels of sugar, and have a longer shelf life, in comparison with conventional sweet corn, and are frequently referred to as supers weet varieties.
  • One specific gene in sweet corn, the shrunken-2 (sh2) gene causes the mature corn kernel to dry and shrivel as it matures past the milky stage, which is an undesirable trait for seedling germination, early emergence and plant growth.
  • the endosperm of conventional sh2 sweet corn kernels store less amounts of starch, and from about 4 to about 10 times more sugar, than conventional sul sweet corn. This has permitted the long-distance shipping of sweet corn, and has enabled manufacturers to can sweet corn without adding extra sugar or salt to it.
  • the third gene mutation is the sel (sugary enhanced- 1) allele, which is incorporated in the genome of Everlasting Heritage varieties.
  • Conventional sweet corn varieties with the sel alleles typically have a longer storage life, and contain from about 12% to about 20% sugar (i.e., a much higher sugar level in comparison with the conventional sul varieties).
  • sweet com must generally be isolated from any field corn varieties that release pollen at the same time.
  • the endosperm develops from genes from both parents (male and female), and kernels will generally be tough and starchy.
  • the most distinguishable sugar component that is present in sweet corn is sucrose, which accounts for the vast majority of its sweetness differentiation. (Abbott and Cobb, Inc., Plant Protection No. 9600094 (1998).)
  • the reducing free sugars, glucose and fructose, are present in sweet corn in significantly lower levels. These reducing sugars primarily result from the natural hydrolysis of sucrose.
  • Many of the endosperm mutant genes in maize (and in other crop plants) that are presently used commercially are listed in Table 1 below. These endosperm mutations all are believed to affect starch synthesis during kernel development, and have been characterized and mapped in maize.
  • the recessive sugary (sul) genotype that is present in sweet corn has an effect of retarding (significantly slowing) a normal conversion of sugar into starch during endosperm development, which very desirably results in a sweet taste, rather than in a starchy taste.
  • This gene has been cloned and mapped to the short arm of chromosome 4 in sweet corn, and its genomic sequence and amino acid sequence translation are set forth in U.S. Patent No. 5,912,413 entitled "Isolation of the SUl Starch Debranching Enzyme, the Product of the Maize Gene Sugary 1," and herein.
  • the sugary (sul) gene encodes a Class II starch debranching enzyme that is active in cellular plastids. It is an isoamylase that hydrolyzes the ⁇ -(l ,6) branch linkages in starch during starch synthesis. (JA Shultz et al., "Current Models for Starch Synthesis and the Sugary
  • Enhancer 1 (se 1) Mutation in Zea maysi," Plant Physiology and Biochemistry 42(6), 457-464 (2004).)
  • the sugary (sul) gene confers a moderate increase in overall sugar levels to corn kernels, but disadvantageously has only about one half of the total sugar content of "supersweet" corn varieties, which is significantly less desirable to corn consumers. Also disadvantageously, the conversion of sugar to starch in the corn kernels is comparatively rapid, generally resulting in a narrow harvest window before the sweetness of the com kernels deteriorates after the prime eating stage (at approximately 75% kernel moisture).
  • the sugary (sul) gene contrary to its name, therefore, does not generally result in exceptionally high levels of sugars. However, it does generally result in greatly increased levels of phytoglycogen or water soluble polysaccharides (WSP).
  • WSP phytoglycogen or water soluble polysaccharides
  • Phytoglycogen and WSP give the endosperm of the kernels of conventional sul sweet corn varieties the smooth texture and creaminess characteristic of traditional sweet corn varieties. Mature endosperm of non- mutant corn generally contains approximately 2% WSP, whereas corn lines that are homozygous for the sugary (sul) gene may contain up to approximately 35% WSP.
  • the sugary enhancer (sel) mutant gene is a recessive modifier of the sugary- 1 (sul) gene mutation.
  • the sugary enhancer (sel) allele increases total sugar in conventional sugary- 1 (sul) variety corn kernels to levels that are comparable to those in shrunken-2 (sh2) variety corn kernels, and without a reduction in phytoglycogen content.
  • sugary enhancer (sel) gene corn kernel elevated total sugars, lighter color, and slow dry down, and were originally observed in an inbred corn line designated as IL1677a. It was only later that these effects were attributed to the sugary enhancer (sel) gene.
  • RA Brink "Identity and Sources of a Sugary Enhancer Gene Located on the Long Arm of Chromosome 4 in Maize," J. Heredity 82, 176 (1991).
  • the sugary enhancer (sel) gene confers a higher moisture content to sweet corn kernels during postharvest periods of time, and also maintains relatively increased levels of
  • the sugary enhancer (sel) gene When both the sugary enhancer (sel) gene and the sugary (sul) gene are recessive, the sugary enhancer (sel) gene very advantageously confers from about 1.5 to about 2 times more sucrose to corn kernels at their peak harvest maturity in comparison with sugary (sul) gene mutant com kernels.
  • the sugary enhancer (sel) gene locus is situated on the long arm of chromosome 2 in sweet corn. Identifiable variants of the sugary enhancer (sel) gene are currently being evaluated and characterized.
  • the enzymatic basis for the sugary enhancer (sel) gene currently does not appear to be known, and the nucleotide sequence of the sugary enhancer (sel) gene currently does not appear to be known, and is not present in the Maize Genetics and Genomics Database or GenBank database.
  • the inheritance of the sugary enhancer (sel) gene can be determined by those having ordinary skill in the art by following nearby molecular markers on chromosome 2, as is described herein. Such a determination may also be made for other mutant genes. Additional information about the sugary enhancer (sel) gene is present in D.R.
  • sh2 shrunken-2
  • AGP ADP-glucose pyrophosphorylase
  • the conventional shrunken-2 (sh2) class of sweet corns (designated as "supersweet”) comprises the vast majority of the U.S. commercial corn market.
  • Mature dry shrunken-2 (sh-2) variety corn kernels contain approximately twice the total sugar content, approximately 1/3 to 1/2 of the starch levels, and only trace levels of phytoglycogen, in comparison with conventional sugary- 1 (sul) variety corn kernels.
  • Shrunken-2 (sh2) type sweet corns generally result in dramatically reduced total carbohydrate levels at peak maturity, and express approximately two or more times the sucrose in comparison with conventional sugary- 1 (sul) mutant sweet corn.
  • sugar retention at the post prime eating stage i.e., during the period of time immediately following the prime eating stage
  • sugar retention at the post prime eating stage i.e., during the period of time immediately following the prime eating stage
  • sugary enhancer- 1 (sel) mutant sweet corns are generally significantly extended relative to conventional sugary- 1 (sul) and sugary enhancer- 1 (sel) mutant sweet corns.
  • shrunken-2 (sh2) gene in the genetic makeup of corn advantageously has an effect of increasing the corn's sweetness. It has also been determined, however, that including this gene in the genetic makeup of corn very
  • conventional shrunken-2 (sh2) varieties of corn generally lack the smooth and creamy texture of the conventional sugary- 1 (sul) and sugary enhancer- 1 (sel) mutant corn varieties as a result of such decreased levels of water soluble polysaccharides.
  • Shrunken-2 (sh2) varieties of sweet corn generally express a markedly collapsed kernel physical appearance at the dry seed stage, and this dry seed "shrunken" appearance, and corresponding reduced kernel starch reserves, tends to render a relatively diminished seedling emergence and vigor at planting time or during germination.
  • precision seeding and stand establishment are markedly more difficult. The germination of such seeds can be problematic both in inbred production and in hybrid stands.
  • dent corn (a species of field corn) has been used as the genetic background for the shrunken-2 (sh2) gene.
  • sh2 shrunken-2
  • the dominant dent corn genes can very disadvantageous ⁇ necessitate an isolation of the hybrid from both field and sweet corn, and any foreign pollen can cause all of the corn kernels to be dent corn in character.
  • sucrose levels, sugar retention (holding) abilities, pericarp levels and changes in pericarp levels of conventional sweet corn varieties containing the sugary- 1 (sul) gene, the sugary enhancer- 1 (sel) gene or the shrunken-2 (sh2) gene at the prime eating stage, or over a seven-day period, are shown in FIGS. 1-4, respectively.
  • sugary- 1 (sul) gene, the sugary enhancer- 1 (sel) gene or the shrunken-2 (sh2) gene at the prime eating stage, or over a seven-day period are shown in FIGS. 1-4, respectively. (Abbott and Cobb, Inc., Plant Protection No. 9600094 (1998).)
  • FIG. 1 provides a generalized comparison of representative endosperm sucrose levels for the conventional sugary- 1 (sul), sugary enhancer- 1 (sel) and shrunken-2 (sh2) genetic mutant lines at the prime eating stage (at a level of approximately 75% moisture).
  • FlG. 1 shows that the sugary-1 (sul) line has the lowest level of sucrose (about 7.5%), followed by the sugary enhancer-1 (sel) line (about 12.5%), and then by the shrunken-2 (sh2) line, which has a much higher level of sucrose in comparison with the other two lines (about 27.5%).
  • FIG. 2 shows the relative endosperm sugar retention or "holding ability" at room temperature for the conventional sugary-1 (sul), sugary enhancer-1 (sel) and shrunken-2 (sh2) genetic mutant lines at the prime eating stage (at a level of approximately 75% moisture) over a seven day interval (Days 1-7). It shows representative changes in endosperm sucrose levels over time for the three different genetic types.
  • sugary-1 (sul) line has the lowest level of sucrose at all times during the 7-day period (ranging from about 4% on Day 1 to about 1% on Day 7), followed by the sugary enhancer-1 (sel) line (ranging from about 12% on Day 1 to about 2% on Day 7), and then by the shrunken-2 (sh2) line, which has a much higher level of sucrose over each of Days 1-7 in comparison with the other two lines (ranging from about 25% on Day 1 to about 13% on Day 7).
  • FIG. 3 provides a comparison of representative pericarp levels for the conventional sugary-1 (sul), sugary enhancer-1 (sel) and shrunken-2 (sh2) genetic mutant lines at the prime eating stage (at a level of approximately 75% moisture).
  • FIG. 3 shows that the sugary enhancer- 1 (sel) line has the lowest level of pericarp (about 0.75%), followed by the sugary-1 (sul) line (about 1.1%), and then by the shrunken-2 (sh2) line, which has a much higher level of pericarp in comparison with the other two lines (about 1.6%).
  • FIG. 4 shows the relative pericarp levels at room temperature for the conventional sugary-1 (sul), sugary enhancer-1 (sel) and shrunken-2 (sh2) genetic mutant lines at the prime eating stage (at a level of approximately 75% moisture) over a seven day interval (Days 1-7). It shows representative changes in pericarp levels over time for the three different genetic types.
  • sh2 line generally has the lowest level of pericarp during the 7-day period (ranging from about 1.6% on Day 1 to about 2.1% on Day 7), followed by the sugary enhancer-1 (sel) line (ranging from about 1.1% on Day 1 to about 4.9% on Day 7) and the sugary-1 (sul) line (ranging from about 1.7% on Day 1 to about 4.9% on Day 7).
  • U.S. Patent No. 6,184,438 Bl describes an identification and characterization of a mutant form of the shrunken-2 (sh2) gene, designated as shrunken-2i (sh2-i).
  • sh2-i shrunken-2i
  • This mutant allele (and variants thereof) is stated to confer enhanced germination characteristics to these plants as compared to maize plants that express the sh2-R gene.
  • This patent describes methods for transforming plants with this mutant allele (and variants), and plants that have this mutant allele incorporated into their genomes.
  • ADP-glucose pyrophosphorylase is a maize endosperm enzyme that is an important enzyme in the synthesis of starch, and catalyzes a conversion of ATP and ⁇ -glucose-1 -phosphate to ADP-glucose and pyrophosphate.
  • ADP-glucose arising from the action of this enzyme is the major donor of glucose for starch biosynthesis in plants.
  • AGP enzymes have been isolated from plant photosynthetic and non-photosynthetic tissues, and is a heterotetramer that contains two different subunits.
  • Maize endosperm ADP-glucose pyrophosphorylase is composed of two dissimilar subunits that are encoded by two unlinked genes, shrunken-2 (sh2) and brittle-2 (bt2). (M.
  • Shrunken-2 (sh2) and brittle-2 (bt2) maize endosperm mutants generally have greatly reduced starch levels, which disadvantageously correspond with greatly reduced or deficient levels of AGP activity. Mutations of either gene have been shown to reduce AGP activity by about 95%.
  • C. Tsai et al. "Starch-Deficient Maize Mutant Lacking Adenosine Diphosphate Glucose Pyrophosphorylase Activity," Science 151:341-343 (1966); D. Dickinson et al., "Presence of ADP-Glucose Pyrophosphorylase in Shrunken-2 and Brittle-2 Mutants of Maize Endosperm," Plant Physiol.
  • Gene splicing is essentially a two-step cleavage-ligation reaction that can produce molecular lesions in genes, such as the wildtype shrunken-2 (sh2) gene.
  • the first step involves the cleavage at the 5' splice site that leads to the formation of an intron lariat with the adenosine residue of the branch point sequence located upstream to the 3' splice site. This is followed by the ligation of the exon and release of the intron lariat.
  • MJ. Moore et al. "Evidence of Two Active Sites in the Spliceosome Provided by Stereochemistry of Pre-mRNA Splicing," Nature 365:364-368 (1993); MJ.
  • This set of events is carried out by pre-mRNA association with a conglomeration of small nuclear RNA (snRNAs) and nuclear proteins that forms a dynamic large ribonucleosome protein complex (a spliceosome).
  • snRNAs small nuclear RNA
  • a spliceosome nuclear proteins that forms a dynamic large ribonucleosome protein complex
  • This fundamental process common to all eukaryotic gene expression, can have a diverse impact on the regulation of gene expression. For example, imprecise or inaccurate pre-mRNA splicing often imparts a mutant phenotype, whereas alternative splicing is sometimes important in the regulation of gene expression.
  • CF. Weil et al. "The Effects of Plant Transposable Element Insertion on Transcription Initiation and RNA Processing," Annu. Rev. Plant Physiol. Plant MoI.
  • the wildtype shrunken-2 (sh2) gene has 16 exons which, in term, are separated by 15 introns, as is shown in FIG. 5. This gene is estimated to be approximately 6000 base pairs long.
  • One intron, in particular, is of significance for the sh2-i allele.
  • This intron, designated “intron 2,” contains at least about 7,800 base pairs in the sh2-i gene.
  • the mutant shrunken-2i (sh2-i) gene is characterized by a single base pair change at the end of intron 2, as is shown in FIGS. 5 and 9.
  • the mutant polynucleotide comprises a substitution of the wild-type terminal base at the end of intron 2 from a G to another base, such as to A, C or T (and not the wild type G nucleotide), and preferably to A.
  • the result would be a change of the AG nucleotide sequence that is found at the terminus of this plant gene intron to an AA sequence at the 3 '-terminus of this intron.
  • the result is a molecular lesion of the sh2-i allele in which it has undergone a G to A mutation at the terminal base of intron 2 in the maize sh2 gene.
  • mutant sh2-i allele when expressed in a plant, such as maize, provides the plant with enhanced growth characteristics, such as germination, seedling, seed and/or plant vigor in combination with desirable consumer traits, such as sweetness.
  • Inbred sweet corn lines containing the mutant sh2-i allele generally demonstrate sweetness, and sugar levels, that are similar to conventional shrunken-2 (sh2) counterparts at the peak eating stage (at approximately 75% moisture). However, at a point in time just past the prime eating stage, mutant sh2-i inbred plant lines initiate a rapid acceleration of starch synthesis. This results in dry seed phenotypes that are physically significantly fuller and heavier than their shrunken-2 (sh2) counterparts and, to some degree, resemble a modified flint corn seed appearance. The net result is an overall enhancement of seed and seedling germination and vigor, and plant vigor, along with associated enhanced plant growth characteristics. This improved germination, and accelerated plant growth phenomenon, directly results in improved varietal crop yield potentials and consistencies.
  • NILs near isogenic lines
  • sh2 conventional shrunken-2 (sh2) hybrid backcross conversions containing, and not containing, the sh2-i allele
  • disadvantageous ⁇ yielded sweetness evaluation scores indicating a rapid starch buildup in the sh2-i hybrids, generally immediately following the prime eating stage.
  • the sh2-i hybrids exhibited reduced sweetness within about 24 to about 48 hours immediately following the prime eating stage, with a corresponding significant sugar degradation and loss at about three days post prime eating stage.
  • FIG. 6 presents mean organoleptic averages for starch accumulation for conventional shrunken-2 (sh2) hybrid near isogenic lines (NILs) that do not contain the mutant shrunken-2i (sh2-i) allele in comparison with those for conventional shrunken-2 (sh2) hybrid corresponding near isogenic lines (NILs) that contain the mutant shrunken-2i (sh2-i) allele over time in Days 1- 7 immediately following the prime eating stage (at a level of approximately 75% moisture).
  • the organoleptic scores range from 1 (sweet with little or no starch taste) to 10 (very little sweetness with a considerable starch taste).
  • shrunken-2i (sh2-i) allele into conventional sweet corn varieties is considered to be impractical due to a rapid accumulation of starch in the period of time immediately following the prime eating state, and the associated loss of holding ability and shelf life.
  • U.S. Patent No. 3,971,161 describes methods that are stated to produce hybrid sweet corn seeds in commercial quantities, increase the sugar content of sweet corn without seriously reducing the water soluble polysaccharide content, and produce seeds that provide a sweet corn suitable for processing with a minimal amount of extraneous sweeteners. It states that the sugar content of sweet corn can be increased without seriously reducing the water soluble polysaccharide content
  • polysaccharide by using the shrunken-2 (sh2) gene and that combining a sweet corn which is a homozygous sugary- 1 (sul) inbred with a sweet corn (homozygous sulsh2) inbred will result in a heterozygous hybrid that has approximately 50% more sucrose, 33% more total sugars and a water soluble polysaccharide level near that of sweet corn (homozygous sul).
  • the high water soluble polysaccharide and sucrose levels are stated to be particularly desirable in food processing industries, such as the canning and freezing industries.
  • U.S. Patents Nos. 5,589,618 and 5,650,557 describe a variant of the maize gene shrunken-2 (sh2) that is designated Sh2-mlRev6, and a method of using that gene.
  • Sh2-mlRev6 is stated to encode a subunit of the ADP-glucose pyrophosphorylase (AGP) enzyme that has additional amino acids inserted in, or near, the allosteric binding site of the protein.
  • Corn seed expressing the Sh2-mlRev6 gene is stated to have a 15% weight increase over wild type seed, and the increase in seed weight is stated not to be associated simply with an increase in percentage starch content of the seed.
  • U.S. Patent No. 5,746,023 describes a method for identifying genetic markers that are stated to be linked to alleles conferring yield potential of a crop species. By conducting genetic marker analysis of a set of current elite lines, and the ancestral population from which they were derived by decades of plant breeding, the '023 patent states that one may determine and compare the expected, and observed, allele frequencies within elite populations at numerous polymorphic loci.
  • U.S. Patent No. 5,912,413 describes the starch debranching enzyme encoded by the sugary (sul) gene that is active in maize ⁇ Zea mays) endosperm, and the cDNA and gene sequences encoding this enzyme.
  • the amino acid sequence of the enzyme is stated to be significantly similar to that of bacterial isoamylases, enzymes that hydrolyze ⁇ -(l ⁇ 6) glycosidic bonds.
  • This patent states that amino acid sequence similarity establishes sul as a member of the ⁇ -amylase super family of starch hydrolytic enzymes.
  • the '413 patent also discloses antibodies that are reactive with the sul protein, methods of producing antibodies to the sul protein, methods of producing fusion proteins including sul, and methods of producing transgenic plants with a modified sul gene.
  • U.S. Patent No. 6,184,438 Bl describes mutant alleles of the genes that encode the large subunit of AGP-glucose pyrophosphorylase in plants, methods for transforming plants with the mutant alleles, and plants that have the mutant alleles incorporated into their genome. When present in maize plants, the mutant alleles are stated to confer enhanced germination
  • U.S. Patent No. 6,756,524 B2 describes an isolation and identification of a nucleic acid molecule that is stated to regulate fruit size and/or cell division in plants, and the protein encoded by this nucleic acid molecule.
  • the '524 patent also describes an expression vector containing the encoding nucleic acid, and methods whereby fruit size is stated to be reduced and/or increased, and cell division is stated to be regulated, by a transformation of plants with this nucleic acid molecule. It also discusses host cells, transgenic plants and plant seeds containing this nucleic acid molecule.
  • U.S. Patent No. 7,084,320 B2 describes methods for selecting a parent inbred plant line (having a particular genetic background) that has a good combining ability, for example, for the production of hybrid plant lines, from a collection of parental lines.
  • a parent inbred plant line is referred to as being "an excellent combiner" in breeding experiments that are described in this patent.
  • the two parent inbred plant lines are stated to be capable of yielding a hybrid plant line with high heterosis effect, and the seeds from the crossed selected inbred lines are collected and, optionally, planted and grown to obtain the hybrid plants.
  • the '320 patent also describes methods for determining the agronomical performance of different plant lines, including the foregoing hybrids, which it states can be performed in vitro by determining the electron flow in mitochondria under control and stress conditions.
  • the '320 patent describes an object as being to provide a method for selecting a hybrid (or other) plant line having the highest growth and yield vigor from a collection of plant lines from the same species (variety). It describes and shows (FIG. 1) a vigor assay that it states can be used to identify plant lines that are affected in their vigor.
  • sh2-i contains a G to A transition at the 3-terminus of intron 2 (LaI et al., Plant Physiol. 120:65-72, 1999), and that approximately 10% of sh2-i transcripts are correctly spliced utilizing the mutant intron splice site, generating a low level of adenosine diphosphate glucose pyrophosphorylase activity that results in the intermediate kernel phenotype.
  • shrunken-2i sh2-i
  • sugary- 1 sul
  • sugary enhancer- 1 saccharide
  • Rogers NK Boise, ID
  • Syngenta Seeds, Inc. Sudon, MN
  • Rogers NK has one commercial maize product (named "Brighton") that includes the maize shrunken-2i (sh2-i) allele in its genome
  • this product has not been commercially successful because the eating quality (taste, texture and the like) of this product is not desirable to consumers. Because this product does not taste good (i.e., it has a starchy, unsweet taste), it has been very undesirable to corn growers and gardeners who are planting sweet corn for consumer acceptance.
  • the present invention provides unique, cost-effective, reliable, efficient and successful methods for developing and producing plants, plant materials and seeds, such as sweet corn kernels, and sweet corn, that very advantageously receive, and have, multiple very desirable attributes for consumers of these products, as well as for commercial plant growers and home gardeners, and to improved plants, plant materials and seeds that are produced in accordance with these methods.
  • inventive methods provide hybrid plants, plant materials and seeds having the mutant shrunken-2i (sh2-i) allele incorporated into their genomes sequentially along with one or more other mutant alleles, such as the sugary- 1 (sul), sugary enhancer- 1 (sel) and/or shmnken-2 (sh2) alleles, and that very advantageously have multiple very beneficial and desirable characteristics, generally including a smooth and creamy texture, an enhanced sugar level that results in a very desirable sweet or other taste, an extended sugar retention ability (and associated taste benefits, such as the sweet taste of sweet corn) at the post prime eating stage, a longer harvest window of the plant, a longer holding ability of the plant (ears of sweet corn and the like), and a longer shelf life of the plant before sweetness deteriorates after the prime eating stage, seeds and/or kernels that physically are fuller, and have a higher carbohydrate and water soluble polysaccharides (WSP) content, at the dry seed stage, and/or significantly enhanced vigor and fitness to the plant, plant material and
  • the present invention provides a method for producing a hybrid plant, plant material or seed that has an enhanced vigor in comparison with a conventional mutant shrunken- 2 (sh-2) or mutant shrunken-2i (sh2-i) hybrid plant, plant material or seed, and an enhanced ability to retain sugar over a period of time immediately following a prime eating stage thereof, in comparison with a conventional mutant sugary- 1 (sul) or shrunken-2i (sh2-i) hybrid plant, plant material or seed, comprising using one or more molecular markers to sequentially include in the genome of the plant, plant material or seed a mutant shrunken-2i (sh2i) allele and one or more other mutant alleles that confer the foregoing characteristics to the plant, plant material or seed.
  • the present invention provides a method for producing a hybrid plant, plant, plant material or seed that has both an enhanced vigor in comparison with a conventional mutant shrunken-2 (sh-2) or shrunken-2i (sh2-i) hybrid plant, plant, plant material or seed, and an enhanced ability to retain sugar over a period of time immediately following a prime eating stage thereof (or one or more other desirable traits), in comparison with a conventional mutant sugary- 1 (sul) or shrunken-2i (sh2-i) hybrid plant, plant, plant material or seed, comprising the following steps in any suitable order:
  • NILs near isogenic lines
  • a female near isogenic plant line having a shrunken-2i (sh2-i) allele layered over a genetic background of sulsul selsel, or of one or more other desirable mutant alleles, in its genome (a female "converted near isogenic line”); (e) optionally, crossing the female converted near isogenic line with a male plant line having a triple homozygous recessive allelic combination of sulsul selsel sh2sh2 (or some other triple homozygous recessive allelic combination that can provide the hybrid plant with a high or enhanced eating quality) in its genome to produce a hybrid plant having one or more desired grower and/or consumer traits; (f) optionally, examining a physical appearance (phenotype) of seeds (or kernels) resulting from the plants of step (d) and/or step (e) for characteristics such as smoothness, fullness and/or relative weight (in comparison with seeds or kernels from conventional or other plants);
  • step (g) optionally, conducting warm, cold and/or other germinations of seeds (or kernels) resulting from the plants of step (d) and/or step (e) to verify that such seeds have one or more desired consumer and/or grower traits, such as an enhanced germination, seedling emergence and plant growth performance, and vigor, that is associated with a mutant shrunken-2i (sh2-i) allele; and
  • step (h) optionally, conducting one or more organoleptic tests on plants (or parts thereof, such as ears of corn) that are grown from seeds (or kernels) produced by plants of step (d) and/or step (e) to determine their taste and/or other organoleptic characteristics, optimally examining the overall physical and horticultural traits (i.e., phenotype) that are consistent with plants that express one or more desired grower and/or consumer traits.
  • organoleptic tests i.e., phenotype
  • a regulation of carbohydrate accumulation and pericarp tenderness (among other traits) can be manipulated in a plant, plant material and/or seed, and a mutant shrunken-2i (sh2-i) allele can be incorporated into the genome of the plant, plant material or seed to give it the desired production and consumer traits.
  • Plants, plant materials and seeds can be grown that exhibit a fuller content at the dry seed stage in comparison with other plant varieties or lines, and result in an enhanced vigor during seed germination, seedling emergence from the soil and/or plant development, and that also maintain an elevated sugar level, resulting in a sweet or other desirable flavor of the plant, plant material and/or seed over a period of time immediately following the prime eating stage thereof.
  • Those having ordinary skill in the art may determine the number of times that a particular step in the above process, such as the
  • the present invention provides a hybrid plant, plant, plant material or seed that has an enhanced vigor in comparison with a conventional mutant shrunken-2 (sh-2) or shrunken-2i (sh2-i) hybrid plant, plant, plant material or seed, and an enhanced ability to retain sugar over a period of time immediately following a prime eating stage thereof, in comparison with a conventional mutant sugary- 1 (sul) or shrunken-2i (sh2-i) hybrid plant, plant, plant material or seed, consisting of steps (a) through (p) above in any suitable order.
  • sh-2 shrunken-2
  • sh2-i shrunken-2i
  • the present invention provides a plant seed that is produced by any one of the methods that is described above.
  • the present invention provides a hybrid or other plant seed comprising a genome including the shrunken-2i (sh2-i) allele that is sequentially layered across a genetic background of one or more additional mutant alleles providing the plant seed with one or more desirable traits, wherein the plant seed is conferred with an enhanced vigor in comparison with a conventional mutant shrunken-2 (sh-2) or shrunken-2i (sh2-i) plant seed, and an enhanced ability to retain sugar over a period of time immediately following a prime eating stage thereof, in comparison with a conventional mutant sugary-1 (sul) or shrunken-2i (sh2-i) plant seed.
  • the present invention provides a hybrid or other plant seed consisting of a genome including the shrunken-2i (sh2-i) allele that is sequentially layered across a genetic background of one or more additional mutant alleles providing the plant seed with one or more desirable traits, wherein the plant seed is conferred with an enhanced vigor in comparison with a conventional mutant shrunken-2 (sh-2) or shrunken-2i (sh2-i) plant seed, and an enhanced ability to retain sugar over a period of time immediately following a prime eating stage thereof, in comparison with a conventional mutant sugary-1 (sul) or shrunken-2i (sh2-i) plant seed.
  • the present invention provides a plant or plant material that is produced by any one of the methods that is described above.
  • the present invention provides a hybrid or other plant or plant material comprising a genome including the shrunken-2i (sh2-i) allele that is sequentially layered across a genetic background of one or more additional mutant alleles providing the plant or plant material with one or more desirable traits, wherein the plant or plant material is conferred with an enhanced vigor in comparison with a conventional mutant shrunken-2 (sh-2) or shrunken-2i (sh2-i) plant or plant material and an enhanced ability to retain sugar over a period of time immediately following a prime eating stage thereof, in comparison with a conventional mutant sugary- 1 (sul) or shrunken-2i (sh2-i) plant or plant material.
  • the present invention provides a hybrid or other plant or plant material consisting of a genome including the shrunken-2i (sh2-i) allele that is sequentially layered across a genetic background of one or more additional mutant alleles providing the plant or plant material with one or more desirable traits, wherein the plant or plant material is conferred with an enhanced vigor in comparison with a conventional mutant shrunken-2 (sh-2) or a
  • FIG. 1 is a bar graph that provides a generalized comparison of representative endosperm sucrose levels for the conventional sugary- 1 (sul), sugary enhancer- 1 (sel) and shrunken-2 (sh2) genetic mutant lines at the prime eating stage (at a level of approximately 75% moisture).
  • FIG. 2 is a line graph that shows the relative endosperm sugar retention or "holding ability" at room temperature for the conventional sugary- 1 (sul), sugary enhancer- 1 (sel) and shrunken-2 (sh2) genetic mutant lines at the prime eating stage (at a level of approximately 75% moisture) through a seven day interval (Days 1-7).
  • FIG. 2 shows representative changes in endosperm sucrose levels over time for the three different genetic types.
  • FIG. 3 is a bar graph that provides a comparison of representative pericarp levels for the conventional sugary- 1 (sul), sugary enhancer- 1 (sel) and shrunken-2 (sh2) genetic mutant lines at the prime eating stage (at a level of approximately 75% moisture).
  • FIG. 4 is a line graph that shows the relative pericarp levels at room temperature for the conventional sugary- 1 (sul), sugary enhancer- 1 (sel) and shrunken-2 (sh2) genetic mutant lines at the prime eating stage (at a level of approximately 75% moisture) through a seven day interval (Days 1-7).
  • FIG. 4 shows representative changes in pericarp levels over time for the three different genetic types.
  • FIG. 5 is a diagram of the wildtype sh2 gene (sh2-R), which is composed of 16 exons (represented by boxes in FIG. 5) that are separated by introns (represented by lines in FIG. 5). This gene is approximately 6,000 base pairs long.
  • the sh2-R gene has a large (at least 7,800 base pair) insertion in the intron 2-exon 4 region (represented by the triangle in FIG. 5). Primers (represented by the arrows in FIG. 5) bordering this insertion will not yield a Polymerase Chain Reaction (PCR) product because of the large size of the insertion.
  • the sh2-i gene has a single base pair change at the end of intron 2, and primers flanking the insertion site of sh2-i will yield a PCR product.
  • FTG. 6 is a line graph that shows mean starch organoleptic scores (organoleptic averages for starch accumulation) for conventional hybrid shrunken-2 (sh2) near isogenic lines (NILs), either containing, or not containing, the sh2-i allele over time in days 1-7 past the prime eating stage (at a level of approximately 75% moisture).
  • FIG. 7 is a line graph that shows organoleptic average sweetness scores for the corn varieties Beyond, Passion and ACX SS 750 IY in the seven day period immediately following the prime eating stage (at a level of approximately 75% moisture). It illustrates the comparative organoleptic sugar levels among these three sweet corn varieties over this seven-day period of time.
  • FIG. 8 is a line graph that shows organoleptic average pericarp tenderness scores for the corn varieties Beyond, Passion and ACX SS 750 IY in the seven day period immediately following the prime eating stage (at a level of approximately 75% moisture). It illustrates the comparative organoleptic pericarp tenderness levels among these three sweet corn varieties over this seven-day period.
  • FlG. 9 shows a schematic representation of the genomic sequence bearing the splice site alterations of the mutant shrunken-2i (sh2-i) allele (exon 1-4). The point mutation that altered the 3' splice site AG to AA of intron 2 in mutant sh2-i is boxed. Arrows joined by lines mark the donor and acceptor sites used during RNA splicing to generate the mutant transcripts.
  • FTG. 10 is a molecular map of samples of individual inbred NILs that were prepared in the experiments that are described in Example 1.
  • SEQ ID NO. 1 is the 7739 base pair genomic nucleotide sequence of a wild type
  • FIG. 1 of U.S. Patent No. 6,184,438 Bl which is incorporated herein in its entirety by reference, also shows the genomic nucleotide sequence of a wild type Shrunken-2 (sh2) allele of Zea Mays. Introns are indicated by lower case letters.
  • Base number 1 is the transcription start site. The arrow indicates the 3'-end of cDNA. Putative TATA, RY dyad and enhancer sequences are underlined.
  • SEQ ID NO. 2 is the cDNA sequence encoding the sugary-1 (sul) allele of Zea Mays, which is also published in U.S. Patent No. 5,912,413.
  • the 2712 base pair nucleotide sequence of the sul cDNA clone includes a sequence of 14 consecutive T residues located at one end of the clone, identifying the polyadenylation site and the 3' end of the mRNA.
  • a continuous open reading frame (ORF) of 789 codons begins 88 nucleotides from the 5' end of the cDNA clone and terminates 240 nucleotides prior to the poly(A) adenylation site. This ORF corresponds to a polypeptide of 789 amino acids (SEQ ID NO. 3).
  • Comparison of the cDNA and a partial genomic sequence (SEQ ID NO: 4) identifies four exons and introns in the genomic DNA.
  • the four exons extend from nucleotide 658 to nucleotide 1107, nucleotide 1352 to nucleotide 1536, nucleotide 1657 to nucleotide 1753, and nucleotide 2076 to nucleotide 2227.
  • the exon sequences or the full sequence of SEQ ID NO: 4 can be used as probes to obtain the full length genomic sequence by methods that are well known by those having ordinary skill in the art.
  • SEQ ID NO. 3 is an amino acid translation of the sugary-1 (sul) nucleotide sequence of the cDNA clone that is shown in SEQ ID NO. 2, which is also published in U.S. Patent No. 5,912,413.
  • SEQ ID NO. 4 is a partial sugary- 1 (sul) genomic nucleotide sequence, which is also published in U.S. Patent No. 5,912,413.
  • SEQ ID NO. 5 is the deduced amino acid sequence of sul (SEQ ID NO. 4), which is also published in U.S. Patent No. 5,912,413.
  • SEQ ID NO. 6 is a nucleotide sequence of the primer umcl551 (a primer for molecular markers for the sugary enhancer- 1 (sel) allele on chromosome T).
  • SEQ ID NO. 7 is a nucleotide sequence of the primer umcl551 (a primer for molecular markers for the sugary enhancer- 1 (sel) allele on chromosome T).
  • SEQ ID NO. 8 is a nucleotide sequence of the primer bnlgl520 (a primer for molecular markers for the sugary enhancer- 1 (sel) allele on chromosome T).
  • SEQ ED NO. 9 is a nucleotide sequence of the primer bnlgl520 (a primer for molecular markers for the sugary enhancer- 1 (sel) allele on chromosome T).
  • SEQ ID NO. 10 is a nucleotide sequence of the primer phi427434 (a primer for molecular markers for the sugary enhancer- 1 (sel) allele on chromosome T).
  • SEQ ID NO. 11 is a nucleotide sequence of the primer phi427434 (a primer for molecular markers for the sugary enhancer- 1 (sel) allele on chromosome T).
  • SEQ ID NO. 12 is a nucleotide sequence of the primer umc2077 (a primer for molecular markers for the sugary enhancer- 1 (sel) allele on chromosome T).
  • SEQ ED NO. 13 is a nucleotide sequence of the primer umc2077 (a primer for molecular markers for the sugary enhancer- 1 (sel) allele on chromosome T).
  • SEQ ID NO. 14 is a nucleotide sequence of the primer umc2174 (a primer for molecular markers for the shrunken-2 (sh2) allele on chromosome 3).
  • SEQ ID NO. 15 is a nucleotide sequence of the primer umc2174 (a primer for molecular markers for the shrunken-2 (sh2) allele on chromosome 3).
  • SEQ ID NO. 16 is a nucleotide sequence of the primer dupssr33 (a primer for molecular markers for the shrunken-2 (sh2) allele on chromosome 3).
  • SEQ ED NO. 17 is a nucleotide sequence of the primer dupssr33 (a primer for molecular markers for the shrunken-2 (sh2) allele on chromosome 3).
  • SEQ ED NO. 18 is a nucleotide sequence of the primer bmcl257 (a primer for molecular markers for the shrunken-2 (sh2) allele on chromosome 3).
  • SEQ ID NO. 19 is a nucleotide sequence of the primer bmcl257 (a primer for molecular markers for the shrunken-2 (sh2) allele on chromosome 3).
  • SEQ ID NO. 20 is a nucleotide sequence of the primer umc2277 (a primer for molecular markers for the shrunken-2 (sh2) allele on chromosome 3).
  • SEQ JD NO. 21 is a nucleotide sequence of the primer umc2277 (a primer for molecular markers for the shrunken-2 (sh2) allele on chromosome 3).
  • SEQ ID NO. 22 is a nucleotide sequence of the primer phi295450 (a primer for molecular markers for the sugary- 1 (sul) allele on chromosome 4).
  • SEQ ID NO. 23 is a nucleotide sequence of the primer phi295450 (a primer for molecular markers for the sugary- 1 (sul) allele on chromosome 4).
  • SEQ ID NO. 24 is a nucleotide sequence of the primer phi308090 (a primer for molecular markers for the sugary- 1 (sul) allele on chromosome 4).
  • SEQ ED NO. 25 is a nucleotide sequence of the primer phi3O8O9O (a primer for molecular markers for the sugary-1 (sul) allele on chromosome 4).
  • SEQ ID NO. 26 is a nucleotide sequence of the primer phiO76 (a primer for molecular markers for die sugary-1 (sul) allele on chromosome 4).
  • SEQ ID NO. 27 is a nucleotide sequence of the primer phiO76 (a primer for molecular markers for the sugary-1 (sul) allele on chromosome 4).
  • SEQ ID NO. 28 is a nucleotide sequence of the primer phiO79 (a primer for molecular markers for the sugary-1 (sul) allele on chromosome 4).
  • SEQ ID NO. 29 is a nucleotide sequence of the primer phiO79 (a primer for molecular markers for the sugary-1 (sul) allele on chromosome 4).
  • agronomy as is used herein means the science of crop production.
  • alleles refers to an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. Alleles are variants of a gene that produce different traits in a gene's characteristics, and can differ in either coding sequences or non-coding sequences.
  • amino acid as is used herein means a molecule that generally contains the basic amino group (NH 2 ), the acidic carboxylic group (COOH), a hydrogen atom (-H) and an organic side group (R) attached to the carbon atom, thus having the basic formula of
  • Amino acids are the building blocks of proteins in which each is coded for by a codon and linked together through peptide bonds. More than 100 amino acids have been found to occur naturally, with each of them differing in their R group. Twenty of them are involved in making up a protein, and are classified as whether they are non-essential or essential. Nonessential amino acids include alanine, arginine, aspartic acid, asparagine, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine. Essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. The abbreviations for amino acids are well known by those having ordinary skill in the art.
  • backcross means to cross (a hybrid or other plant) with one of its parents, or with an individual that is genetically identical or similar to one of its parents.
  • carbohydrates as is used herein means simple organic compounds comprising carbon, oxygen and hydrogen, generally with many hydroxyl groups added (usually one on each carbon atom that is not part of the aldehyde or ketone functional group).
  • the basic carbohydrate units are monosaccharides, such as glucose, galactose and fructose.
  • Carbohydrates have numerous roles in living things, such as the storage and transport of energy (e.g., starch or glycogen) and structural components (e.g., cellulose in plants). They serve as energy stores, fuels, and metabolic intermediates.
  • Ribose and deoxyribose sugars form part of the structural framework of RNA and DNA.
  • Polysaccharides are structural elements that are present in the cell walls of plants. Carbohydrates are linked to many proteins and lipids, where they play key roles in mediating interactions between cells and interactions between cells and other elements in the cellular environment. Monosaccharides can be linked together into polysaccharides, in a large variety of ways.
  • cellular respiration means a series of metabolic processes that generally take place within a cell in which biochemical energy is harvested from an organic substance, such as glucose, and is stored as energy carriers (ATP) for use in energy-requiring activities of the cell. It consists of glycolysis, citric acid cycle or Krebs Cycle, and oxidative phosphorylation. The cell appears to "respire” in a way that it takes in molecular oxygen (as an electron acceptor) and releases carbon dioxide (as an end product) (an aerobic process). Cellular respiration is essential to both eukaryotic and prokaryotic cells because biochemical energy is produced to fuel many metabolic processes, such as biosynthesis, locomotion, transportation of molecules across membranes, and the like.
  • ATP energy carriers
  • prokaryotic cells While the entire process generally occurs in the cytoplasm of prokaryotes, in eukaryotes, generally glycolysis occurs in the cytoplasm, whereas the Krebs Cycle and oxidative phosphorylation occur in the mitochondrion. While prokaryotic cells can generally yield a maximum of 38 ATP molecules, eukaryotic cells can generally yield a maximum of 36 ATP molecules.
  • coding sequence refers to a portion of a gene or an mRNA that codes for a protein.
  • codon means a set of three adjacent nucleotides (triplets), in mRNA that base-pair with the corresponding anticodon of tRNA molecule that carries a particular amino acid, hence specifying the type and sequence of amino acids for protein synthesis.
  • GCC Guideanine-Cytocine-Cytocine
  • GUU Guanine-Uracil- Uracil
  • CUA Cytosine-Uracil-Adenine
  • UCA User-Cytosine- Adenine
  • hybrid plant, plant material, seed, line or variety as is used herein in connection with a sugary- 1 (sul), sugary enhancer (sel), shrunken-2 (sh2), shrunken-2i (sh2-i) or other mutant allele means that the hybrid plant, plant material, seed, line or variety is a typical hybrid plant, plant material, seed, line or variety that generally only includes one mutant allele in its genome that confers the traits that are described herein, rather than a sequential or other combination of two or more mutant alleles, for example, one that includes the mutant shrunken-2i (sh2-i) allele in its genome, but not the sugary- 1 (sul), sugary enhancer (sel) or shrunken-2 (sh2) mutant alleles, or one that includes the mutant sugary- 1 (sul) allele in its genome, but not the sugary enhancer (sel), shrunken-2 (sh2) or shrunken-2i (sh2-i) mutant alleles.
  • corn and “maize” as is used herein means any of numerous cultivated forms of a widely grown, usually tall annual cereal grass (Zea mays) bearing grains or kernels on large ears, and includes the numerous varieties of sweet corn and supersweet corn.
  • the grains or kernels of this plant may be used as food for humans and livestock, or for the extraction of an edible oil or starch.
  • the kernels may be eaten raw or cooked, and may be canned, frozen and/or stored in other manners that are known by those of ordinary skill in the art.
  • cross means the act of mixing different species or varieties of plants to produce hybrids.
  • a monohybrid cross is a breeding experiment between parental generation organisms that differ in one trait. In a monohybrid cross, there is generally a genetic cross between parents that differ in the alleles they possess for one particular gene, with one parent having two dominant alleles, and the other parent having two recessive alleles. All of the offspring (monohybrids) then have one dominant and one recessive allele for that gene (i.e. they are hybrid at that one locus).
  • a dihybrid cross is a breeding experiment between parental generation organisms that differ in two traits. In a dihybrid cross, there is generally a genetic cross between parents that differ in two characteristics, controlled by genes at different loci.
  • Gregor Mendel performed a dihybrid cross using pea plants and the characteristics of seed color and texture.
  • the parental plants had either smooth yellow seeds (SSYY) (the dominant characteristics) or wrinkled green seeds (ssyy) (the recessive characteristics).
  • All of the offspring had smooth yellow seeds, being heterozygous (SsYy) for the two alleles.
  • Crossing between these offspring produced an F 2 generation of plants with smooth yellow, smooth green, wrinkled yellow, and wrinkled green seeds in the ratio 9:3:3:1.
  • Mendel used these results as the basis for his Law of Independent Assortment.
  • a trihybrid cross is a breeding experiment between parental generation organisms that differ in three traits, and so forth.
  • crop as is used herein means the periodic, such as annual or seasonal, yield of any plant that is grown in significant quantities to be harvested as food, as livestock fodder, as fuel or for any other economic (or other) purpose.
  • crops are used for industrial purposes, for example, they are grown and harvested for the sole purpose of making profit and feeding people, and are grown in large quantities in certain areas that are suitable for growing crops.
  • the term "dominant” as is used herein means an allele or a gene that is expressed in an organism's phenotype, generally masking the effect of the recessive allele or gene when present.
  • the dominant allele or gene is the one that determines the phenotype of an organism. Its effects are readily recognized in comparison with the effects of the recessive allele or gene.
  • a dominant allele is symbolized with a capital letter, and a recessive allele is symbolized with a small letter, for example: Hh (where H refers to the dominant allele and h refers to the recessive allele).
  • dry seed stage means the first temporal event in the germination of a plant, such as sweet corn, and in which the seed or kernel contains a moisture content that is generally less than about 12%.
  • D.B Uncan's New Multiple Range Test
  • MRT Mean a multiple comparison statistical procedure that uses the studentized range statistic q r to compare sets of means, and is particularly protective against false negative (Type II) error. This test is commonly used in agronomy and in other types of agricultural research, and is well known by those having ordinary skill in the art. Additional information about this test is present in D.B.
  • embryo as is used herein means a young plant developed from an ovum sexually or asexually and, in seed plants, contained within the seed.
  • endosperm as is used herein means the nutritive tissue that is found in many seeds of plants, and that surrounds the embryo within such seeds. It supplies nutrients to the embryo.
  • the endosperm is generally the site of most starch deposition during kernel development in maize, and endosperm starch content comprises approximately 70% of the dry weight of the kernel or seed.
  • energy means the ability to do work or produce change.
  • Energy exists in different forms, but is neither created nor destroyed. It simply converts to another form, and can be expressed in joules or ergs. Energy is often stored by cells in biomolecules, such as carbohydrates (sugars) and lipids. The energy is generally released when these molecules have been oxidized during cellular respiration, and is carried and transported by
  • ATP an energy-carrier molecule
  • enzyme means a protein (or protein-based molecule) that generally speeds up a chemical reaction in a living organism, such as a plant. Enzymes generally act as catalysts for specific chemical reactions, converting a specific set of reactants (substrates) into specific products. Enzyme generally have a characteristic sequence of amino acids that fold to produce a specific three-dimensional structure, which gives the molecule unique properties, and are usually classified and named according to the reaction that they catalyze.
  • episis means that a mutation in one gene masks the expression of a different gene. (In contrast, with dominance, one allele of a gene masks the expression of another allele of the same gene.)
  • exon refers to those portions of a genomic DNA sequence that will be represented in a final, mature mRNA (i.e., a contiguous segment of genomic DNA that codes for a polypeptide in a gene).
  • the term “exon” may also refer to equivalent segments in a final RNA. Exons may include coding sequences, a 5' untranslated region and/or a 3' untranslated region.
  • express means to manifest the effects of a gene, to cause to produce an effect or a phenotype, or to manifest a genetic trait, depending upon the context.
  • the expression of a gene is the translation of information encoded in the gene into protein or RNA.
  • Expressed genes include genes that are transcribed into messenger RNA (mRNA) and then translated into protein, as well as genes that are transcribed into types of RNA, such as transfer RNA (tRNA) and ribosomal RNA (rRNA) that are not translated into protein.
  • tRNA transfer RNA
  • rRNA ribosomal RNA
  • Gene regulation gives the cell control over structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of an organism, such as a plant.
  • fittest refers to a measure of the relative breeding success of an organism, such as a plant, or genotype, in a given population at a given time. Individuals that contribute the most offspring to the next generation are the fittest. Fitness therefore reflects how well an organism is adapted to its environment, which determines its survival.
  • the term "gene” as is used herein refers to the basic unit of heredity (genetic traits) in a living organism (plant, animal or micro-organism) that holds the information that is required to pass genetic traits to offspring. It is a segment of deoxyribonucleic acid (DNA) that contributes to a phenotype/ function.
  • the DNA is a molecule in the shape of a double helix, with each rung of the spiral ladder having two paired bases selected from adenine (A), thymine (T), cytosine (C) or guanine (G). Certain bases always pair together (AT and GC), and different sequences of base pairs form coded messages. Genes are arranged in precise arrays all along the length of chromosomes, which are much larger structures.
  • genetic map means a diagram that shows the genetic linkage relationships among loci on chromosomes (or linkage groups) within a given species. "Mapping” is the process of defining the linkage relationships of loci through the use of genetic markers, populations that are segregating for such markers, and standard genetic principles of recombination frequency. A “map location” is a specific locus on a genetic map where an allele can be found within a given species.
  • gene as is used herein means the complete set of genes in an organism, such as a plant, or the total genetic content in one set of chromosomes, depending upon the context.
  • genotype refers to an organism's inherited instructions that it carries within its genetic code.
  • a genotype for a gene is generally the set of alleles that it possesses.
  • breeding means the process by which a dormant seed emerges from a period of dormancy, and begins to sprout and grow into a seedling under the right growing conditions.
  • the most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. It is the growth of an embryonic plant contained within a seed, and results in the formation of a seedling.
  • glucose as is used herein means a simple monosaccharide sugar that serves as the main source of energy, and as an important metabolic substrate for most living things. Its chemical formula is C 6 H 12 O 6. Glucose is one of the products of photosynthesis in plants, and the glucose molecules are stored as repeating units of sugar (e.g. starch). Glucose also serves as an important metabolic intermediate of cellular respiration.
  • slaughter means the gathering (collecting and/or assembling) of a crop of any kind, for example, of maize.
  • heterozygous as is used herein means having dissimilar alleles that code for the same gene or trait.
  • An example is a zygote having one dominant allele and one recessive allele, i.e., Aa, for a particular trait.
  • homologous as is used herein in connection with chromosomes means those that contain identical linear sequences of genes, and which pair during meiosis. Each homologue is a duplicate of one of the chromosomes contributed by one of the parents, and each pair of homologous chromosomes is normally identical in shape and size.
  • homozygosity means the presence of identical alleles at one or more loci (a specific place on a chromosome where a gene is located.) in homologous chromosomal segments.
  • hybrid means an offspring resulting from a cross between parents of different species or sub-species (i.e., from crossbreeding).
  • a single cross hybrid is a first generation of offspring resulting from a cross between pure bred parents.
  • a double cross hybrid is offspring resulting from a cross between two hybrids of single cross.
  • a three-way cross hybrid is offspring from a cross between a single cross hybrid and an inbred line.
  • a triple cross hybrid is offspring resulting from the crossing of two different three-way cross hybrids.
  • hybridization means the act or process of mating organisms of different varieties or species to create a hybrid.
  • Independent Assortment refers to a separation of the alleles of one gene into the reproductive cells (gametes) independently of the way in which the alleles of other genes have segregated. By this process, all possible combinations of alleles should occur equally frequently in the gametes. In practice, this does not always happen because alleles that are situated on the same chromosome tend to be inherited together. However, if the allele pairs Aa and Bb are on different chromosomes, the combinations AB, Ab, aB, and ab will normally be equally likely to occur in the gametes.
  • inbred means offspring produced by inbreeding (succeeding generations of organisms, such as plants, that are all derived by breeding from the same group of closely related organisms). When lines are inbred sufficiently, a homozygous condition of particular alleles can generally be assumed.
  • inbreeding means the breeding of related organisms within an isolated or a closed group of organisms. It is the continued breeding of closely related organisms, so as to preserve desirable traits in a therein.
  • intron refers to portions of genomic DNA that are not coding sequences. While they are transcribed (and thus present in the primary transcript), they are later spliced out. They, thus, are not present in the corresponding mature mRNA.
  • locus refers to a specific chromosome location in the genome of a species where a specific type of gene can be found.
  • Mendel's Laws refers to the two laws that summarize Gregor Mendel's theory of inheritance, which are the foundation of genetics.
  • the Law of Segregation states that each hereditary characteristic is controlled by two "factors' (alleles), which segregate (separate) and pass into separate germ (reproductive) cells.
  • the Law of Independent Assortment states that pairs of "factors' (alleles) segregate independently of each other when germ cells are formed.
  • molecular marker means a specific fragment of DNA that can be identified within a whole genome. Molecular markers are generally found at specific locations of a genome, and are used to 'flag' the position of a particular gene or the inheritance of a particular characteristic. In a genetic cross, the genes producing characteristics of interest will usually stay linked with the molecular markers in relatively close proximity on the chromosome. Thus, varieties can be selected in which the molecular marker is present, since the marker indicates the presence of the desired characteristic. Examples of molecular markers include simple sequence repeats (SSRs), single nucleotide polymorphisms (SNPs), randomly amplified polymorphic DNA (RAPDs), and restriction fragment length polymorphisms (RFLPs).
  • SSRs simple sequence repeats
  • SNPs single nucleotide polymorphisms
  • RAPDs randomly amplified polymorphic DNA
  • RFLPs restriction fragment length polymorphisms
  • multiple means more than one, for example, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen, twenty, twenty five, thirty, thirty-five, forty, forty- five, fifty, fifty-five, sixty and so forth.
  • number may also include one.
  • mutant refers to a permanent, heritable change of genetic material, either in a single gene or in the numbers or structures of the chromosomes.
  • a mutation occurs when a gene is changed in such a way as to alter the genetic message carried by that gene.
  • the mRNA transcribed from that gene will now carry an altered message, and the polypeptide made by translating the altered mRNA will now contain a different sequence of amino acids.
  • the function of the protein made by folding this polypeptide may also be changed or lost. In subtle or very obvious ways, the phenotype of the organism carrying the mutation may be changed.
  • Mutation may be small scale (affecting the nucleotide sequence of a gene) or large scale (involving a change in the chromosome). It may arise from deletions (the deletion of one or more nucleotides in the genetic material), insertions (an insertion of one or more extra nucleotides into a new place in the genetic material) or substitutions (an exchange of one or more nucleotides for another in the genetic material, for example, switching an A to a G), as may be caused by exposure to ultraviolet or ionizing radiation, chemical mutagens, viruses or the like.
  • a substitution may: (i) change a codon to one that encodes a different amino acid, and cause a small change in the protein produced; (ii) change a codon to one that encodes the same amino acid, and causes no change in the protein produced; or (iii) change an amino-acid-coding codon to a single "stop" codon and cause an incomplete protein.
  • Mutations may result in the creation of a new character or trait. Mutations may increase an organism's fitness, which may spread through the population over successive generations by natural selection. Mutation is the ultimate source of genetic variation, and a particular mutant gene or allele may be compared to its corresponding wild type gene or allele to determine the differences between the two genes or alleles. There are different types of mutations.
  • a point mutation is a single nucleotide substitution within a gene, and there may be several point mutations within a single gene. Point mutations generally do not lead to a shift in reading frames and, thus, at most generally cause only a single amino acid substitution. Because protein-coding DNA is divided into codons that are three bases long, insertions and deletions can alter a gene so that its message is no longer correctly parsed. These changes are known as "frameshifts.” In frameshifts, a similar error occurs at the DNA level, causing the codons to be parsed incorrectly. This usually generates truncated proteins that useless. Additional information regarding mutations is present in Mutation: Science of Everyday Things (Gale Group, 2002).
  • NILs near isogenic lines, which are lines of a plant, such as sweet corn, that are genetically identical, except for one locus.
  • organoleptic testing means a testing of the physical and/or chemical changes that are inherent to decomposition. It may be performed on food, such as sweet corn, to measure and evaluate the temperature, taste, smell, texture and/or other properties that are capable of eliciting a response in the sensory organs of human beings or animals.
  • Organoleptic refers to the sensory properties of a substance, such as taste, color, odor and/or feel, and organoleptic testing involves inspection through tasting, feeling, smelling and/or visual examination of a substance.
  • phenotype as is used herein means an observable characteristic or trait of an organism, such as sweet corn, such as its morphology, development and/or biochemical or physiological properties. Phenotypes generally result from the expression of an organism's genes, as well as the influence of environmental factors, and possible interactions between the two. In natural populations, most phenotypic variation is continuous, and is effected by alleles at one or multiple gene loci.
  • plant as is used herein means any organism that that belongs to Kingdom Plantae, and that is characterized by the following features:
  • organs are specialized for anchorage, support and photosynthesis (e.g. roots, stems,
  • Plants are the major producers in an ecosystem, and they include, for example, trees, herbs, bushes, grasses, vines, ferns and mosses.
  • Examples of particular plants include, but are not limited to, lettuce, tobacco, cotton, corn, rice, wheat, carrot, cucumber, leek, pea, melon, potato, tomato, sorghum, rye, oat, sugarcane, peanut, flax, bean, sugar beets, soya and sunflower plants.
  • plasmid as is used herein means any of several generally pigmented cytoplasmic organelles that are found in plant cells, having various physiological functions, such as the synthesis and storage of food.
  • pleotropic means producing multiple effects from a single gene.
  • the Marfan gene is pleiotropic and can cause long fingers and toes, dislocation of the lens of the eye and dissecting aneurysm of the aorta.
  • polystyrene as is used herein means the fine powder-like material consisting of pollen grains that contain the male reproductive cells of most plants. Pollen is generally produced by the anthers of seed plants.
  • pollenation means the process by which plant pollen is transferred, generally from the anther to the stigma (from male reproductive organs to the female reproductive organs) of a plant to produce offspring (to form seeds).
  • pollen is transferred from the anther to the stigma, often by the wind or by insects.
  • male cones release pollen that is usually borne by the wind to the ovules of female cones.
  • the pollen grain generally contains two cells: a generative cell and a tube cell.
  • the generative nucleus generally divides to form two sperm nuclei.
  • the tube cell generally grows down into the pistil until it reaches one of the ovules contained in the ovary.
  • the two sperm generally travel down the tube and enter the ovule, where one sperm nucleus generally unites with the egg.
  • the other sperm nucleus generally combines with the polar nuclei that exist in the ovule, completing a process known as "double fertilization.”
  • These fertilized nuclei then generally develop into the endocarp, the tissue that feeds the embryo.
  • the ovule itself generally develops into a seed that is contained in the flower's ovary (which ripens into a fruit). In gymnosperms, the ovule is exposed (not contained in an ovary), and the pollen produced by the male reproductive structures lands directly on the ovule in the female reproductive structures.
  • PCR polymerase chain reaction
  • Primers are added (which initiate the copying of each strand) along with nucleotides and heat stable Taq polymerase. By cycling the temperature, the target DNA is repetitively denatured and copied. Because the newly synthesized DNA strands can subsequently serve as additional templates for the same primer sequences, successive rounds of primer annealing, strand elongation, and dissociation produce rapid and highly specific amplification of the desired sequence.
  • PCR also can be used to detect the existence of the defined sequence in a DNA sample.
  • PCR can be used to amplify RNA sequences if they are first converted to DNA via reverse transcriptase.
  • PCR buffers, primers, probes, controls, markers, amplification kits, sDNA synthesis kits, general PCR kits, and the like are available from sources that are known by those having ordinary skill in the art, such as Applied Biosystems (Foster City, CA), and may readily be used by those having ordinary skill in the art in accordance with the present invention.
  • primary eating stage and “peak eating stage” as are used herein mean the stage when a plant, such as sweet corn, tastes the most favorable or sweetest, which may readily be determined by those having ordinary skill in the art and, for sweet corn, may be when the corn kernels contain approximately 75% moisture.
  • sweet corn tends to mature all at once, and when it is past its prime eating stage, the sweetness generally becomes diminished or absent, and is replaced by a bland, starchy flavor, which is not desirable to consumers.
  • nucleotide as is used herein means the basic building block (subunits) of nucleic acids, such as DNA and RNA. It is an organic compound that is generally made up of nitrogenous base, a sugar and a phosphate group. DNA molecule consists of nucleotides in which the sugar component is deoxyribose, whereas the RNA molecule has nucleotides in which the sugar is ribose. The most common nucleotides are divided into purines and pyrimidines based upon the structure of the nitrogenous base. In DNA, the purine bases include adenine and guanine, while the pyrimidine bases are thymine and cytosine.
  • RNA includes adenine, guanine, cytosine and uracil instead of thymine.
  • nucleotides also serve as important cofactors in cellular signaling and metabolism. These cofactors include flavin adenine dinucleotide (FAD), flavin mononucleotide, adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP).
  • FAD flavin adenine dinucleotide
  • ATP adenosine triphosphate
  • NADP nicotinamide adenine dinucleotide phosphate
  • a DNA oligonucleotide is a short piece of DNA composed of relatively few (oligo-) nucleotide bases.
  • peripheral means the wall of a plant fruit, such as a corn kernel, which generally is developed from an ovary wall, and contains an outer exocarp, a central mesocarp and an inner endocarp.
  • phytoglycogen as is used herein means a plant polysaccharide having a structure that is similar to glycogen, and similar properties.
  • the phytoglycogen present in sweet corn is a water soluble glycan having an average unit chain length of 13, reflecting a generally high degree of branching.
  • polynucleotide as is used herein means an organic polymer molecule that is composed of nucleotide monomers covalently bonded in a chain.
  • DNA deoxyribonucleic acid
  • RNA ribonucleic acid
  • polysaccharide as is used herein means any of a class of carbohydrates, such as starch and cellulose, consisting of a number of monosaccharides that are joined by glycosidic bonds.
  • protein refers to a large molecule composed of one or more chains of amino acids in a specific order, which is determined by the base sequence of nucleotides in the gene that is coding for the protein. Proteins are required for the structure, function, and regulation of cells, and each protein has unique functions.
  • the term "recessive" as is used herein in connection with a gene means a gene whose phenotypic effect is expressed in the homozygous state, but is masked in the presence of the dominant allele (i.e. when the organism is heterozygous for that gene).
  • the dominant gene produces a functional product whereas the recessive allele does not: both 1 dose and 2 doses per nucleus of the dominant allele, therefore, generally lead to an expression of its phenotype, whereas the recessive allele is generally observed only in the complete absence of the dominant allele.
  • seed as is used herein means a propagating organ formed in the sexual reproductive cycle of gymnosperms and angiosperms (male and female sex cells) that includes a protective coat enclosing an embryo and food reserves. It is a small hard fruit that is generally located in a fertilized ovule of a plant. A seed has two main components, the embryo and the endosperm. The endosperm acts as a food store for the embryo which, over time, will grow from this rich food supply that enables it to do so. Most seeds go through a period of quiescence in which there is no active growth. During this time, the seed can be safely transported to a new location and/or survive adverse climate conditions until it is favorable for growth.
  • the seed contains an embryo and, in most plants, stored food reserves wrapped in a seed coat. Under favorable growth conditions, a seed begins to germinate, and the embryonic tissues resume growth, developing towards a seedling. Additional information about seeds, seedlings, germination and plant growth is present in P. Raven et al., Biology of Plants (7th Edition, New York: W. H. Freeman and Company), 504-508 (2005); and B. Larkins et al., Cellular and Molecular Biology of Plant Seed Development (Kluwer Academic Publishers, 1997).
  • seedling as is used herein means a young plant sporophyte developing out of a plant embryo from a seed. Seedling development starts with the germination of the seed.
  • a typical young seedling consists of three main parts: (i) the radicle (embryonic root); (ii) the hypocotyl (embryonic shoot); and (iii) the cotyledons (seed leaves).
  • the young plant emerges from its protective seed coat generally with its radicle first, followed by the cotyledons. The radicle orients towards gravity, while the hypocotyl orients away from gravity and elongates through cell expansion to push the cotyledons out of the ground.
  • seedling development starts with skotomorphogenesis while the seedling is growing through the soil and attempting to reach the light as fast as possible.
  • the cotyledons are tightly closed and form an apical hook to protect the shoot apical meristem from damage while pushing through the soil.
  • the seed coat still covers the cotyledons for extra protection.
  • the seedling's developmental program is generally switched to photomorphogenesis.
  • the cotyledons generally open upon contact with light (splitting the seed coat open, if still present) and become green, forming the first photosynthetic organs of the young plant.
  • the seedling generally lives off of the energy reserves that are stored in the seed.
  • the opening of the cotyledons generally exposes the shoot apical meristem and the plumule, consisting of the first true leaves of the young plant. Seedlings sense light through the light receptors phytochrome (red and far-red light) and cryptochrome (blue light). Once a seedling starts to photosynthesize, it generally is no longer dependent on the seed's energy reserves.
  • the apical meristems start growing and give rise to the root (the organ of the plant that typically lies below the surface of the soil) and shoot (new plant growth, such as stems and leaves).
  • the first "true" leaves generally expand, and can often be distinguished from the round cotyledons through their species-dependent distinct shapes. While the plant is growing and developing additional leaves, the cotyledons eventually senesce and fall off.
  • allelism analysis means a method for confirming allelism. This may be performed by crossing two lines that are homozygous but contain different alleles at a locus in question. One may then monitor segregation of the alleles in segregating generations to test for expected Mendelian segregation patterns. Homology of DNA fragments to the same probe and mutual exclusivity among diverse inbred lines is generally a reasonable test of allelism.
  • selfing means manually pollinating a plant by placing its pollen on its own stigma, and it is a breeding strategy that can lead to homozygosity of an allele. If a set of parents are homozygous for the same allele, this allele is simply transmitted and the progeny will generally be homozygous for this same allele. On the other hand, if the parents are homozygous, but for different alleles, A and B, then the progeny is a heterozygote A/B if a single cross is made, but is homozygous A or B, each with an expectation of 1/2 if the cross is followed by many selfings.
  • sh2-i mutant allele means mutant alleles or genes that contain the same intron splice site point mutation that is described and shown herein, and confer the same trait(s) as are described herein, whether designated as sh2-i or by some other designation, such as by sh2-N2340.
  • soil as is used herein nieans any kind of a medium, or mixture of mediums, in which a plant seed, such as a maize seed, will typically reasonably grow into a plant, such as the unconsolidated mineral or organic material that is present on the surface of the Earth, which serves as a natural medium for the growth of land plants.
  • a plant seed such as a maize seed
  • Such mediums are known by those having ordinary skill in the art.
  • starch as is used herein means a polysaccharide carbohydrate that generally includes a large number of glucose monosaccharide units that are joined together by glycosidic bonds, and is found in plant seeds, bulbs and tubers. Starch is generally predominantly present as amylase and amylopectin. Plants use starch as a way to store excess glucose, and as food during mitochondrial oxidative phosphorylation.
  • saccharide as is used herein means a disaccharide made up of glucose and fructose that is present in many plants, and is widely used as a sweetener or preservative.
  • sugar as is used herein means any disaccharides (e.g. sucrose) and monosaccharides (e.g. fructose or glucose).
  • Sugars are essential structural component of living cells, and are a source of energy for many organisms, such as plants. Plants use sugars to store energy. Sugars are classified based on the number of monosaccharide units that are present in the molecule. The monosaccharides join to form more complex sugars, e.g. disaccharides.
  • test cross means the crossing of an organism, such as a plant, with an unknown genotype, to a homozygous recessive organism (tester). It is a cross between an individual of unknown genotype or a heterozygote (or a multiple heterozygote) to a homozygous recessive individual.
  • trait refers to a distinguishing quality or characteristic, and is generally a distinct variant of a phenotypic character of an organism, such as sweet corn, that may be inherited and/or environmentally determined, for example, the sugar content of sweet corn.
  • the goal of plant breeding in general is to produce progeny that exceed their parents in terms of performance for one or more traits.
  • progeny may be identified using techniques that are known by those having ordinary skill in the art, such as segregation analyses. In order to observe transgressive segregation, parents that complement one another in terms of favorable alleles at various loci must generally be selected. Crossing and recombination can then result in progeny that contain more favorable alleles than either parent.
  • RNA synthesis is the process of transcribing DNA nucleotide sequence information into RNA sequence information. Both nucleic acid sequences use complementary language, and the information is simply transcribed, or copied, from one molecule to the other. DNA sequence is enzymatically copied by RNA polymerase to produce a complementary nucleotide RNA strand (messenger RNA or mRNA) because it carries a genetic message from the DNA to the protein-synthesizing machinery of the cell.
  • RNA polymerase a complementary nucleotide RNA strand
  • mRNA messenger RNA or mRNA
  • transcription is the first step that usually leads to the expression of the genes, by the production of the mRNA intermediate, which is a faithful transcript of the gene's protein-building instruction.
  • the stretch of DNA that is transcribed into an RNA molecule is the transcription unit.
  • a DNA transcription unit that is translated into protein contains sequences that direct and regulate protein synthesis in addition to coding the sequence that is translated into protein.
  • the regulatory sequence that is before (upstream (-), towards the 5' DNA end) the coding sequence is the 5' untranslated region, and regulatory sequence that is found following (downstream (+), towards the 3' DNA end) the coding sequence is the 3' untranslated region.
  • the RNA is synthesized in the 5' ⁇ 3' direction.
  • This strand is the template strand because it provides the template for ordering the sequence of nucleotides in an RNA transcript.
  • the other strand is the coding strand because its sequence is the same as the newly created RNA transcript (except for uracil being substituted for thyamine).
  • the DNA template strand is read 3' - ⁇ 5' by RNA polymerase and the new RNA strand is synthesized in the 5'—» 3' direction.
  • a polymerase binds to the 3' end of a gene (promoter) on the DNA template strand and travels toward the 5' end. Transcription is divided into 5 stages: pre- initiation, initiation, promoter clearance, elongation and termination.
  • translation means the process by which polypeptide chains are synthesized, the sequence of amino acids being determined by the sequence of bases in a messenger RNA, which in turn is determined by the sequence of bases in the DNA of the gene from which it was transcribed. Additional information regarding translation is present in D. V. Lim, Microbiology (3rd ed., Kendal/Hunt, 2003).
  • vigor means an exertion of force or a measure of the increase in plant growth and/or foliage volume through time after planting (i.e., after the proper setting of seeds into the ground for propagation), and/or of some other superior quality related to seed, seedling and/or plant strength and/or growth, such as an enhanced germination and/or seedling emergence out of the ground, depending upon the context.
  • a plant line can be called “vigorous” when the line grows vitally, healthy, is tolerant to various biotic and abiotic stresses and/or has a high yield, possibly even while under sub-optimal conditions.
  • Vigor can be measured, and compared for different plant varieties (or for particular lines within a particular plant variety), by methods that are known by those having ordinary skill in the art, in terms of percents (from 0% to 100%), or otherwise, and the higher the growth and yield of a particular plant variety (or line) (in seeds, fruits, vegetables, plants and/or the like), the more vigor the plant generally has. For example, one sweet corn variety or line may produce approximately 10% fewer kernels when compared with another sweet corn variety or line.
  • yield vigor is described in U.S. Patent No.
  • yield refers to plant, plant material and/or seed productivity, such as the productivity per unit area of a particular plant product of commercial significance. For example, yield of soybean is commonly measured in bushels of seed per acre, or metric tons of seed per hectare, per season.
  • wildtype refers to a native or predominant genetic constitution before mutations, usually referring to the genetic constitution normally existing in nature.
  • the present invention provides unique, cost-effective, reliable, efficient and successful methods for developing and producing plants, plant materials and seeds, such as corn kernels, and corn, that receive, and have, multiple very desirable attributes for consumers of these products, as well as for commercial plant growers, and to improved and/or enhanced plants, plant materials and seeds that are produced in accordance with these methods.
  • These inventive methods very advantageously provide inbred, hybrid and other plants, plant materials and seeds that have multiple very beneficial and desirable characteristics or traits, generally including those that are described below (as well as others), even when subjected to reasonable amounts of environmental or other stresses, such as cooler temperatures, drought conditions, low nutrients and other poor soil conditions, crowding, disease, insects, animals, pollution and/or the like.
  • the corn kernels physically are fuller, and have a higher carbohydrate and water soluble polysaccharides (WSP) content, at the dry seed stage in comparison with conventional shrunken-2 (sh2) and shrunken-2i (sh2-i) mutant gene corn varieties (and other corn varieties, such as wildtype corn varieties), which have greatly reduced carbohydrate and, thus initial and subsequent energy levels, and/or water soluble polysaccharides levels.
  • WSP carbohydrate and water soluble polysaccharides
  • conventional sugary- 1 (sul), sugary enhancer- 1 (sel) and shrunken-2 (sh2) sweet corn varieties and even with sweet corn varieties including all three of these mutant alleles, and in some cases are better in eating quality than such sweet corn varieties (and other sweet corn varieties, such as wildtype corn varieties).
  • the corn kernels contain elevated total sugar levels (2 to 3 times the sugar levels of many conventional corn varieties), resulting in a very desirable sweet flavor and taste of these kernels, in comparison with conventional sugary- 1 (sul) mutant gene corn varieties, and other corn varieties, which is very desirable to consumers when eating the corn kernels.
  • corn kernel sugar levels can be quantified using methods that are known by those having ordinary skill in the art, such as gas chromatography.
  • the sugar retention, and associated sweet taste, of the corn kernels at the post prime eating stage is significantly extended in comparison with conventional sugary- 1 (sul) and shrunken-2i (sh2-i) mutant gene corn varieties (and other corn varieties), which have a rapid conversion of sugar to starch during this period of time (resulting in a loss of sugar), and an associated reduction in sweet taste of the corn kernels, and a narrow harvest window before sweetness deteriorates very soon after the prime eating stage.
  • the corn kernels have a reduced starch accumulation at, and to a practical point following, the prime eating stage (peak eating quality), such as from about 1-14 days immediately following the prime eating stage, in comparison with conventional sugary- 1 (sul) and shrunken-2i (sh2-i) mutant gene corn varieties (and other corn varieties).
  • peak eating quality such as from about 1-14 days immediately following the prime eating stage, in comparison with conventional sugary- 1 (sul) and shrunken-2i (sh2-i) mutant gene corn varieties (and other corn varieties).
  • the corn kernels of hybrid maize varieties that are produced in accordance with the methods of the invention are smooth and attractive, sweet, tender, plump and creamy, and have a high eating quality, all of which is very desirable to consumers worldwide.
  • Corn breeders, corn producers, corn growers, scientists and others have not been able to produce a sweet corn that includes each of the above, and very desirable, production and consumer traits (i.e., these combined traits). Further, the present inventor spent more than four years conducting experiments to attempt to successfully develop and produce hybrid varieties of sweet corn that include these very desirable combined traits, and that include the shrunken-2i (sh2-i) mutant allele along with one or more other mutant alleles, and were finally surprisingly and unexpectedly able to accomplish this goal.
  • the methods of the present invention combine specific mutant alleles that are present in sweet corn, or other plants, with the shrunken-2i (sh2-i) gene.
  • the mutant alleles which include, but are not limited to, sugary- 1 (sul), sugary enhancer (sel), and shrunken-2 (sh2), when expressed in a sweet corn (or other plant) hybrid in combination with the shrunken-2i (sh2-i) gene, provide enhanced growth characteristics, such as germination and seedling vigor, to the sweet corn, as well as the other very beneficial characteristics that are described hereinabove.
  • the methods of the present invention preferably provide a unique, sequential layering of sul sul, sel sel, in
  • the methods of the invention involve the use, and identification of, commercial (and other) hybrid, inbred and other plant lines containing the above mutant alleles, either singly or in combination, and exceed conventional expectations relative to seedling and plant growth characteristics. These mutant alleles confer elevated sweetness, and reduced kernel pericarp, differentially in specific combination.
  • the problem to be solved by the present invention was to manipulate the regulation of carbohydrate accumulation and pericarp tenderness in sweet corns containing the shrunken-2i (sh2-i) gene.
  • the examples that are set forth herein describe experiments that were performed in order to solve this problem and achieve this goal.
  • Plant seeds, plant materials and plants that may be produced in accordance with the methods of the present invention include those that are capable of having the shrunken-2i (sh2-i) mutant allele, and at least one other beneficial mutant allele, including, but not limited to, the mutant sugary- 1 (sul), sugary extender- 1 (sel) and/or shrunken-2 (sh2) alleles, incorporated into their genome, and expressed, in a manner that produces the beneficial combined grower and consumer traits that are described herein, which may be determined by those having ordinary skill in the art.
  • the invention involves a unique sequential combination or layering of the shrunken-2i mutant (sh2-i) allele with the mutant sugary (sul), sugary enhancer (sel) and/or shrunken-2 (sh2) alleles in sweet corn.
  • the unique sequential layering of sul sul, sel sel in combination with the mutant sh2i allele functions to preserve enhanced seedling germination and vigor along with product holding ability and shelf life, and provide sweet corn (and other plants) with the other beneficial traits that are described herein.
  • nucleotide sequences of some of the mutant genes that may be employed in the methods of the present invention are set forth herein.
  • nucleotide sequences of other mutant genes that may be employed in the invention, and related or other nucleotide sequences may be readily obtained from sources that are known by those having ordinary skill in the art, such as from the Maize Genetics and Genomics and/or GenBank databases.
  • the Maize Genetics and Genomics database is a community database for biological information about the crop plant Zea mays, and is funded by the USDA Agricultural Research Service. The following data types are accessible through this site: genetic, genomic, sequence, gene product, functional characterization, literature reference, and person/organization contact information.
  • GenBank sequence database is an open access, annotated collection of all publicly available nucleotide sequences and their protein translations. This database is produced at the National Centers for Biotechnology Information, which is a branch of the National Institutes of Health (Bethesda, MD), and is available on line via the Entrez search engine. GenBank and its collaborators receive sequences produced in laboratories throughout the world from more than 100,000 distinct organisms, and it continues to grow at an exponential rate, doubling every 18 months. It contains over 65 billion nucleotide bases in more than 61 million sequences.
  • DNA-based markers allows a plant breeder to identify physical characteristics at the molecular level, thus lending a scientific hand in creating and replicating plant varieties.
  • Plant breeding and seed production programs can be enhanced by applying molecular markers for trait selection and mapping, or variety and hybrid genotyping. They provide vehicles for locating and comparing loci regulating quantitative traits requires a segregating population of plants. Each one may be genotyped using molecular markers.
  • a molecular marker showing polymorphism between the parents of a population which is closely-linked to a gene regulating a particular trait will mainly co-segregate with that gene and the observable trait (i.e., segregate according to the phenotype if the gene has a large effect).
  • the frequency of the two marker alleles present within each of the two bulks should deviate significantly from the ratio of 1:1 expected for most populations.
  • the map location of closely-linked genes can, therefore, be deduced without having to genotype every individual in segregating populations. This can be used with composite populations of maize and other crops and plants to locate quantitative trait loci that are associated with various traits.
  • the inheritance of the gene can still be determined by those having ordinary skill in the art by following nearby molecular markers on the chromosome including the gene, as is described in the Examples section herein in detail.
  • Primers for the molecular markers that were used in the Examples appearing herein are publicly available, and may be found in the Maize Genetics and Genomics database at the Internet site maizegdb dot org. The following are primers for examples of useful molecular markers.
  • SSR simple sequence repeats
  • Isoelectric Focusing Electrophoresis This company provides molecular services for an identification, and incorporation of, specific sweet corn mutant alleles.
  • SSR simple sequence repeats
  • sweet corn is grown in soil having a pH ranging from about 6 to about 6.5 in full sun, with a planting depth of about 1 inch. Fertilization is typically performed when the sweet corn plants reach about 12" in height for tall varieties, and from about 18" to about 24" in height for other varieties. The sweet corn plants are typically harvested at approximately 64 days after seedlings emerge. As is known by those having ordinary skill in the art, the foregoing conditions may be varied.
  • STA Laboratories (Longmont, CO) performs physical purity and vigor analyses using Seedling Vigor Imaging System (SVIS), as well as other seed analyses services. Registered Seed Technologists (RST) ensure uniform testing standards to meet seed labeling regulations in the United Stated and abroad. STA Seed Health Laboratories are USDA accredited through the National Seed Health System (NSHS). Other Variations
  • nucleotide sequences encoding portions or all of the mutant alleles that are described herein are contemplated as being within the scope of the present invention, so long as substantially the same phenotype and characteristics observed with the conventional (unaltered) nucleotide sequence is exemplified.
  • the nucleotide mutations of introns contemplated within the scope of the present invention can also be associated with, or used in conjunction with, other mutations of the genes encoding plant AGP polypeptide or encoding other proteins or enzymes. These other mutations include, but are not limited to, mutations in the wild-type sequence that confer other
  • agronomically desirable traits such as heat stability, disease resistance, and other desirable characteristics in a plant expressing these mutant alleles.
  • a mutation of the terminal nucleotide of intron 2 of the Shrunken-2 (sh2) genomic nucleotide sequence is specifically exemplified herein.
  • mutations of the terminal nucleotide in other Shrunken-2 (sh2) introns are also within the scope of the invention, as long as these confer substantially the same characteristics to a plant expressing the allele as those associated with the mutation at intron 2, i.e., germination and seedling vigor comparable to or better than plants expressing wild-type Shrunken-2 (sh2) allele, but with enhanced food or taste quality of the vegetable comparable to, or better than, that associated with mutants that provide enhanced sweetness, such as the Sh2-R allele, over wild-type.
  • Those having ordinary skill in the art, and having the benefit of the teachings that are described herein can readily prepare mutations in other introns of the gene, and determine whether the mutated introns confer the desired characteristics to the plants.
  • Plants that are contemplated within the scope of the invention include, for example, maize, sweet peas, tomatoes, bananas and any other plant in which a high sucrose content of the vegetable or fruit and germination, seedling and plant growth vigor, are desired characteristics.
  • Other plants that are contemplated within the scope of the invention include those that are described elsewhere herein.
  • plant material such as plant tissue, cells or seeds, that contain the polynucleotides that are described herein.
  • Applied Biosystems sells internationally via its web site (applied biosystems dot com) and otherwise a wide variety of different products and computer software for conducting DNA sequencing, DNA synthesis (by ligation, Capillary Electrophoresis or the like), DNA and RNA modification and labeling, DNA and RNA purification, gene expression, genotyping, PCR, peptide synthesis, protein sequencing, transcription, translation, various assays, and the like, such as expression vectors, probes, primers, which may be readily employed by those having ordinary skill in the art for carrying out the present invention.
  • NILs Near Isogenic Lines
  • su 1 su 1 selsel sh2sh2 exotic limited commercial type with exceptional eating quality
  • STA Laboratories assisted in providing the molecular services involved in the identification, and incorporation, of specific sweet corn mutant alleles into the genomes of maize plants.
  • Commercially available appropriate maize marker libraries specifically, simple sequence repeats (SSR), were obtained for trait identifications. Approximately 330 SSR markers were tested, primarily targeting the sul, sel, and sh2 published genomic chromosomal sites.
  • the NILs were backcrossed and self pollinated a sufficient number of times in a manner known by those of ordinary skill in the art to effect an adequate reconstitution of the recurrent parents.
  • Molecular markers were utilized in a manner known by those of ordinary skill in the art to assist in the identification of sul and sel mutant alleles, in particular. These molecular markers were helpful in mutant genotypic identification in that the incorporation of the sh2-i mutant gene provides a dominant phenotype that masks the expression of the sul, sel or sh2 mutant genes.
  • BCl-Sl is an
  • BCl-Sl is a genetic or plant breeder's word for point in time relating to the progress of the final product.
  • the final product in this example is a reconstruction of the recurrent parent in which the sh2-i mutant allele is to be added.) Only those BCl-Sl ears segregating sul, sh2 and sh2-i kernel types were selected for continued
  • the mutant sh2sh2 morphological kernel appearance is distinct in that dry seeds appear translucent, highly collapsed, and wrinkled.
  • the mutant sh2-i kernel phenotypes are smooth, heavier, well filled and nearly flint field corn in appearance (having round kernels with smooth coats). Kernel phenotypes were confirmed with molecular markers, as is discussed elsewhere herein, and shown in FIG. 10. The limitation of but two phenotypes on BC2-S1 selected ears resulted in the verification that the kernels expressing the sh2-i gene were layered over an sulsul sh2sh2 background.
  • Kernels from the BCl-Sl selected sh2-i phenotypes were then planted and test crossed to selsel genetically confirmed inbreds.
  • Molecular marker genetic confirmations were conducted concomitantly. Only plants exhibiting homozygous sel test cross positives and sel molecular confirmations were kept for continued backcrossing, selfing and test crossing. The backcrossing, selfing and test crossing, and molecular confirmations, were continued through six cycles. At this point, it was considered that the original sulsul selsel sh2sh2 NILs were adequately converted with the inclusion of the mutant sh2-i gene.
  • FIG. 10 provides a molecular map for samples of individual inbred NILs.
  • This molecular map :
  • Samples 1-2 (017 and 044, respectively) are genetically: SuISuI SelSel sh2sh2.
  • Samples 3-7 (006, 007, 009, 047 and 637, respectively) are genetically: SuISuI selsel sh2sh2.
  • Samples 8-13 (001, 046, 048, 049, 109 and 354, respectively) are genetically: sulsul selsel sh2sh2.
  • Sample 14 is the donor source for the mutant sh2-i gene.
  • FIG. 10 Highlighted in FIG. 10 are the purported chromosomal regions characterized as the SeI, SuI and Sh2 sites. Numerous molecular markers were useful in genotypic identification. In particular, the molecular marker designated “umc 1551” was efficacious in selsel characterizations, and the molecular marker designated as "phi 079" was similarly useful in making sulsul identifications. Numerous other markers that are shown in FTG. 10 were helpful singly, or in combination, in making marker assisted assignments.
  • Example 2 Example 2
  • the mutant sh2-i gene was incorporated into selected inbred corn lines, as is discussed in Example 1. These inbreds were chosen on the basis of horticultural and seed production criteria.
  • sh2-i conversion inbreds would be used only as female parents in commercial maize production. This decision was based upon a number of factors. One such factor for using the sh2-i conversion parents as females was based upon the fact that kernel pericarp is 2N and maternally inherited. Utilization of the sh2-i parent as female preserves the enhanced germination and seedling vigor characteristic of the sh2-i gene. In addition, commercial seed production yields appear to be greatly enhanced as an artifact of the superior germination and vigor of the sh2-i seed parental lines.
  • male genotype was chosen on its ability to provide desirable horticultural qualities, but primarily by its contribution to high eating quality.
  • Male parental genotypes were utilized that contained sulsul selsel sh2sh2 mutant alleles.
  • FTG. 7 illustrates the comparative organoleptic sugar scores among three sweet corn varieties over a period of seven days directly following the peak eating stage.
  • the commercial variety Passion is sold and distributed through Monsanto (St. Louis, MO).
  • the commercial variety Beyond is sold and distributed by Abbott and Cobb, Inc. (Trevose, PA), and has served as a standard, primarily in the Southeast commercial shipping markets.
  • the variety designated as ACX SS 7501 Y is a hybrid variety that was produced in accordance with Examples 1 and 2.
  • the organoleptic score ranges from 1 (very little sweetness with a considerable starch taste) to 10 (sweet with little or no starch taste).
  • ACX SS 7501Y hybrid corn variety very advantageously maintained an organoleptic sweetness score above both the Passion and Beyond corn varieties at all times during this 7-day period and, in contrast with the Passion and Beyond corn varieties, maintained a score of 10 on days 1 and 2 past prime eating stage. It also shows that the ACX SS 750 IY hybrid corn variety had an organoleptic sweetness score of almost 8 on day 7 (in comparison with a score of about 5 for Passion, and a score of about 3 for Beyond). Over the seven day testing period, the ACX SS 750 IY hybrid corn variety held, and maintained, very high sweetness levels compared to the comparison varieties of Passion and Beyond.
  • FIG. 8 shows the comparative organoleptic pericarp and tenderness scores among the same three sweet corn varieties that are shown in FIG. 7 over a period of seven days directly following the peak eating stage.
  • the organoleptic scores range from 1 (very tough pericarp) to 10 (very tender pericarp).
  • FIG. 8 shows that the ACX SS 7501 Y hybrid corn variety very advantageously maintained an organoleptic pericarp and tenderness score above both the Passion and Beyond corn varieties at all times during this 7 -day period. It also shows that the ACX SS 7501 Y hybrid corn variety had an organoleptic pericarp and tenderness score of about 7 on day 7 (in comparison with a score of about 5 for Passion, and a score of about 2 for Beyond).
  • ACX SS 7078Y is an isogenic conversion of the Abbott and Cobb, Inc. commercially-available hybrid designated ACX 1073Y, which does not have the sh2-i mutant allele incorporated into its genome.
  • ACX SS 7403RY is an isogenic conversion of the Abbott and Cobb, Inc. commercially-available variety designated
  • ACX 7473RY which also does not have the sh2-i mutant allele incorporated into its genome.
  • sh2-i gene containing hybrid developments the isogenic hybrids were found to be nearly identical for all horticultural and morphological characteristics, when identified using methods that are described herein and/or are known by those having ordinary skill in the art.
  • Table 3 below provides data resulting from actual comparisons of laboratory warm and cold germination data, as well as organoleptic tests, for the sweet corn varieties ACX 1073Y, ACX SS 7078Y, ACX 7473 RY and ACX SS 7403RY.
  • Germination data reflect the mean of three replications of 100 kernels each, and germination scores not followed by the same letter are significantly different at the .05 probability level via the Duncan's New Multiple Range Test. The organoleptic tests regarding sweetness and pericarp tenderness are described previously herein. Table 3 shows that, in both cases in which the sh2-i mutant gene was added to the sweet corn genomes, the isogenic hybrid comparison warm and cold laboratory scores were elevated, which is indicative of enhanced field emergence and vigor.
  • Table 3 also shows that the two sweet corn varieties including the mutant sh2-i gene retained their sweetness longer (having scores of 8 on Day 7 in the seven day period immediately following the prime eating stage) than the two sweet corn varieties that did not include this gene (having scores of 6 or 5 on Day 7), and had pericarps that retained their tenderness longer (having scores of 7 on Day 7 in the seven day period immediately following the prime eating stage) than the two sweet corn varieties that did not include this gene (having scores of 6 or 5 on Day 7).
  • the sweetness and pericarp tenderness scores that are present in Table 3 demonstrate acceptable eating quality levels with
  • Two resulting sweet corn sh2-i hybrids of particular interest were designated AC 15 IY and AC 188 W.
  • the inbred line AC 15 IY (including the mutant sh2-i gene) is an isogenic comparison to an Abbott and Cobb, Inc. inbred designated AC 128Y (not including the mutant sh2-i gene).
  • AC 128Y (not including the mutant sh2-i gene).
  • the only significant genetic difference between these two inbred lines in this example is the presence of the mutant sh2-i gene in inbred line AC 15 IY.
  • the inbred line AC 188W (including the mutant sh2-i gene) is an isogenic comparison to an Abbott and Cobb, Inc. inbred designated AC 116W (not including the mutant sh2-i gene). Again, the only significant genetic difference between these two inbred lines in this example is the presence of the mutant sh2-i gene in AC 188W.
  • Table 4 below provides data resulting from actual comparisons of laboratory warm and cold germination data, as well as organoleptic tests, for the sweet corn varieties AC 15 IY, AC 128 Y, AC 188 W and AC 116 W. Germination scores are means of three replications of 100 kernels each. Laboratory scores not followed by the same number are significantly different at the .05 probability level via the Duncan's New Multiple Range Test. The organoleptic tests regarding sweetness and pericarp tenderness are described previously herein. Table 4 shows that, in both cases in which the sh2-i mutant gene was added to the sweet corn genomes, the isogenic hybrid comparison warm and cold laboratory scores were elevated, which is indicative of enhanced field emergence and vigor.
  • Table 4 also shows that the two sweet corn varieties including the mutant sh2-i gene did not retain their sweetness longer (having scores of 2 and 3 on Day 7 in the seven day period immediately following the prime eating stage) in comparison with the two sweet corn varieties that did not include this gene (having scores of 5 and 7 on Day 7), and had pericarps that did not retain their tenderness longer (having scores of 1 and 2 Day 7 in the seven day period immediately following the prime eating stage) in comparison with the two sweet corn varieties that did not include this gene (having scores of 3 and 2 on Day 7).
  • mutant sh2-i gene materials in the manner that has been described previously herein in order to obtain maximum benefits desired by plant growers and consumers (i.e., using molecular markers and an selsel and sulsul genetic background).
  • Sweet Corn Hybrids ACX SS 7501 Y. ACX SS 7078Y and ACX SS 7403RY In the experiments that are described in this example, the physical characteristics of sweet corn hybrids ACX SS 7501 Y, ACX SS 7078Y and ACX SS 7403RY, all of which include the mutant sh2-i gene in their genomes, and have the beneficial benefits that are described herein, were examined and compared using methods that are known by those having ordinary skill in the art. The results of these examinations and comparisons are set forth in Table 5 below.

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BRBR112012003137-6A BR112012003137A2 (pt) 2009-08-12 2009-08-12 Método para produzir uma plata híbrida, planta, material de planta ou semente, planta, semente de planta, e, material de planta.
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CN116536448A (zh) * 2023-06-27 2023-08-04 广东省农业科学院作物研究所 一种与甜玉米的果糖量和产量紧密连锁的kasp分子标记及其应用

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WO2017090944A1 (ko) * 2015-11-24 2017-06-01 서울대학교산학협력단 ｓｕｇ-1 유전자 및 ｓｕｇ-2 유전자를 이용한 식물체 배유의 당 함량, 전분 함량 또는 형태를 조절하는 방법 및 그에 따른 식물체
US11083153B2 (en) 2016-09-26 2021-08-10 Sakata Seed Corporation Sweet corn and method for producing same
CN116536448A (zh) * 2023-06-27 2023-08-04 广东省农业科学院作物研究所 一种与甜玉米的果糖量和产量紧密连锁的kasp分子标记及其应用
CN116536448B (zh) * 2023-06-27 2023-11-10 广东省农业科学院作物研究所 一种与甜玉米的果糖量和产量紧密连锁的kasp分子标记及其应用

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