CN106480061B - Recombinant nucleic acid fragment RecCR023411 and detection method thereof - Google Patents

Abstract

The present application provides recombinant nucleic acid fragments and methods for their detection. The application also provides a breeding method of the rice plant containing the recombinant nucleic acid segment, and the rice plant containing the recombinant nucleic acid segment is obtained by performing foreground selection and background selection on the recombinant plant by using the molecular marker.

Description

Recombinant nucleic acid fragment RecCR023411 and detection method thereof

Technical Field

The present application relates to whole genome selection breeding techniques. In particular, the application relates to a rice plant containing a recombinant nucleic acid fragment by using a whole genome selective breeding technology, the recombinant nucleic acid fragment obtained by the breeding technology and a detection method thereof.

Background

Brown planthopper, academic name Nilaparvata lugens (

) Belonging to the order homoptera, the family planthopper. The brown planthopper is a monophagic pest, only eats rice, and has the characteristics of preference for warmth, weak cold resistance, short growth period, long-distance migration, outbreak property, rampant property and the like. The brown planthopper is a typical piercing-sucking pest, takes the phloem and xylem sap as raw materials, has large food intake and rapid propagation, and can cause no particle harvest in the affected area once the brown planthopper breaks out greatly. In addition, it can also transmit rice virus diseases (such as grass-like bushy stunt and odontoblast disease) and cause serious harm to rice production.

Over 30 sites resistant to brown planthopper have been identified from wild rice and cultivated rice since the 80's of the 20 th century. Due to the complexity of phenotypic identification of brown planthoppers, the individual genes Bph14, Bph26 and Bph3, etc., have been cloned only in recent years (Du et al, PNAS.2009,106(52): 22163-22168; Tamura et al, Sci Rep.2014,4: 5872; Liu et al, Nature Biotechnology.2015,33: 301-305). In addition, with the continuous utilization of the brown planthopper resistant variety in production, the adaptability of the brown planthopper to the variety is gradually enhanced. Some resistant varieties widely used in production are gradually losing resistance to brown planthopper (Deen et al, Rice Genet Newsl.2010,25: 70-72). Currently, the control of brown planthopper still depends on chemical pesticide, which not only increases production cost and pollutes environment, but also promotes the drug resistance of brown planthopper to be enhanced.

Therefore, the cultivation requirement of the new variety of brown planthopper resistance is very urgent.

Disclosure of Invention

In one aspect, the present application provides a recombinant nucleic acid fragment selected from the group consisting of: i) a sequence comprising nucleotides 1274-1810 as shown in SEQ ID NO. 1 or a fragment or variant thereof or the complement thereof; ii) a sequence comprising the sequence shown in SEQ ID NO. 1 or a fragment or variant or complement thereof; iii) a sequence comprising nucleotides 216-773 of SEQ ID NO. 2 or a fragment or variant or complement thereof; or iv) a sequence comprising the sequence shown in SEQ ID NO. 2 or a fragment or variant or complement thereof; and combinations of the above fragments. In one embodiment, the recombinant nucleic acid fragment is a genomic recombinant nucleic acid fragment.

In addition, the present application provides primers for detecting the recombinant nucleic acid fragment selected from the group consisting of: (I) a forward primer which specifically recognizes the sequence of nucleotides 1 to 1274 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 1810-1979 of the sequence shown in SEQ ID NO. 1; (II) a combination of a first set of primer pairs and a second set of primer pairs comprising (a) the first set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 1 to 1274 of the sequence shown by SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 1275 and 1809 of the sequence shown by SEQ ID NO. 1; and (b) a second set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 1275-1809 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 1810-1979 of the sequence shown in SEQ ID NO. 1; (III) a forward primer specifically recognizing the sequence comprising nucleotides 1274 and 1275 of the sequence shown by SEQ ID NO. 1 and a reverse primer specifically recognizing the sequence comprising nucleotides 1809 and 1810 of the sequence shown by SEQ ID NO. 1; (IV) a forward primer specifically recognizing the sequence comprising nucleotides 1274 and 1275 of the sequence shown by SEQ ID NO. 1 and a reverse primer specifically recognizing the sequence of nucleotides 1810 and 1979 of the sequence shown by SEQ ID NO. 1; (V) a forward primer which specifically recognizes the sequence of nucleotides 1 to 1274 of the sequence shown by SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence comprising nucleotides 1809 and 1810 of the sequence shown by SEQ ID NO. 1; and/or optionally, (VI) a forward primer specifically recognizing the sequence of nucleotides 1 to 216 of the sequence shown by SEQ ID NO. 2 and a reverse primer specifically recognizing the sequence of nucleotides 773-994 of the sequence shown by SEQ ID NO. 2; (VII) the following third and fourth sets of primer pairs, comprising (c) the third set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 1 to 216 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 217 and 772 of the sequence shown by SEQ ID NO. 2; and (d) a fourth set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotide No. 217 and 772 of the sequence shown in SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotide No. 773 and 994 of the sequence shown in SEQ ID NO. 2; (VIII) a forward primer specifically recognizing the sequence comprising nucleotides 216 and 217 of the sequence shown by SEQ ID NO. 2 and a reverse primer specifically recognizing the sequence comprising nucleotides 772 and 773 of the sequence shown by SEQ ID NO. 2; (IX) a forward primer which specifically recognizes a sequence comprising nucleotides 216 and 217 of the sequence shown in SEQ ID NO:2 and a reverse primer which specifically recognizes nucleotides 773 and 994 of the sequence shown in SEQ ID NO: 2; (X) a forward primer which specifically recognizes a sequence of nucleotides 1 to 216 of the sequence shown by SEQ ID NO:2 and a reverse primer which specifically recognizes a sequence comprising nucleotides 772-773 of the sequence shown by SEQ ID NO: 2.

In one embodiment, the primer pairs used to amplify the sequences shown in SEQ ID NO. 1 are, for example, 5'-AATAGTCCGACCTGGAATGAAAT-3', and 5'-TCTTTCGAGC GGATCTAATGC-3'. Sequencing primers for detecting the sequence shown in SEQ ID NO. 1 are, for example, 5'-AATAGTCCGACCTGGAATGAAAT-3'; 5'-ACCGCTTCCC TATCCTATTT-3', respectively; 5'-CTGTGATTTGCTATGGGTAA-3', respectively; and 5'-TCTTT CGAGCGGATCTAATGC-3'.

In another embodiment, the primer pairs used to amplify the sequences shown in SEQ ID NO. 2 are, for example, 5'-TCATGCTCCCCATGATCTTGTT-3', and 5'-AATTATGTG CCTCCGTACCACC-3'. The sequencing primers used to detect the sequence shown in SEQ ID NO. 2 are, for example, 5'-TCATGCTCCCCATGATCTTGTT-3'; 5'-CGAGACTTG AAAGCCACAGA-3', respectively; and 5'-AATTATGTGCCTCCGTACCACC-3'.

In another aspect, the present application provides a method for breeding rice plants containing recombinant nucleic acid fragments, comprising the steps of crossing a rice recipient plant parent not containing a target genomic fragment as a recurrent parent with a rice donor plant containing the target genomic fragment, backcrossing the resultant hybrid with the recurrent parent, and then selfing the resultant backcrossed, wherein the recombinant plants are subjected to foreground selection and background selection using molecular markers. For example, the recombinant nucleic acid fragments are as described above.

In the above method, the molecular marker for the foreground selection is selected from one or more of BphC04ID06, RM6659, and BphC04S 08; and/or performing the background selection by using a rice whole genome breeding chip.

In one embodiment, the present application provides a method for breeding rice plants containing brown planthopper resistant genomic recombinant nucleic acid fragments, comprising the steps of: 1) hybridizing the recurrent parent and a donor plant, performing backcross on the obtained hybrid and the recurrent parent to obtain a backcross first generation, performing screening of single-side homologous recombination fragments of brown planthopper resistant genome fragments by using a positive selection marker BphC04ID06 and negative selection markers RM6659 and BphC04S08, and performing background selection on the brown planthopper resistant genome fragments by using a RICE whole genome breeding chip, such as RICE 6K; 2) selecting a recombinant single plant with better background recovery (the background recovery value of the generation exceeds 75 percent) to carry out backcross with recurrent parents again to obtain a second backcross generation, detecting the second backcross generation by using a positive selection marker BphC04ID06, selecting the recombinant single plant containing brown planthopper resistant genome fragments, and then carrying out background selection by using a RICE whole genome breeding chip, such as RICE 6K; 3) selecting a recombinant single plant with a recovered background (the background recovery value of the generation exceeds 87.5 percent) to carry out backcross with a recurrent parent again to obtain three backcross generations, carrying out homologous recombination fragment screening on the other side of the brown planthopper resistant genome fragment by utilizing a positive selection marker BphC04ID06, a negative selection marker RM6659 and BphC04S08, and carrying out background selection on the recombinant single plant by utilizing a RICE whole genome breeding chip, such as RICE 60K; and 4) selecting a recombinant single plant with small introduced segment and good background recovery (the background recovery value exceeds 93.75%), selfing the selected recombinant single plant once to obtain a selfed seed, detecting the selfed seed by using a forward selection marker BphC04ID06, and performing background selection on the selfed seed by using a RICE whole genome breeding chip, such as RICE60K to finally obtain a RICE plant which contains a homozygous brown planthopper resistant genome recombinant nucleic acid segment and has background recovery (the background recovery value exceeds 99%).

In another embodiment, the amplification primers used in the foreground selection of recombinant plants using molecular markers comprise: a primer pair for amplifying a molecular marker BphC04ID06, wherein the forward primer is 5'-CCTAGCCGTCAGGTTAATAGATCAT-3', and the reverse primer is 5'-ACCAGGTCTACTAGCTTTTACGGAG-3'; a primer pair for amplifying a molecular marker RM6659, wherein the forward primer is 5'-TGTGGAGGCTTAGGAAATT CTGG-3', and the reverse primer is 5'-TGTGAAACATGCCACGATACTGC-3'; the primer pair for amplifying the molecular marker BphC04S08, wherein the forward primer is 5'-GAGCGATCCATTAGCACGTGACT-3', and the reverse primer is 5'-GTTTCTAG GTGTTCCCAACTCTCCC-3'.

In still another aspect, the present application provides a method for detecting a recombinant nucleic acid fragment, which comprises the steps of designing specific primers based on the recombinant nucleic acid fragment as described above, performing a PCR reaction using a genome to be detected as a template, and analyzing the PCR amplification product. Specifically, for example, the primer is as described above. Alternatively, PCR amplification products were analyzed using Sanger sequencing.

Specifically, in the method for detecting the recombinant nucleic acid fragment provided by the application, the primer combination for amplifying and detecting the sequence shown in SEQ ID NO. 1 is as follows: amplification primers, including a forward primer: 5'-AATAGTCCGACCTGGAATGAAAT-3', and reverse primer: 5'-TCTTTCGAGCGGATCTAATGC-3', respectively; sequencing primers, including a forward primer: 5'-AATAGTCCGACCTGGAATGAAAT-3', reverse primer: 5'-ACCGCTT CCCTATCCTATTT-3', reverse primer: 5'-CTGTGATTTGCTATGGGTAA-3' and reverse primer: 5'-TCTTTCGAGCGGATCTAATGC-3' are provided. The method comprises the steps of taking genome DNA of a sample to be detected as a template, carrying out PCR amplification by using the amplification primer, sequencing an obtained amplification product by using the sequencing primer, and if a sequencing result is consistent with or complementary to a sequence of SEQ ID NO. 1, determining that the sample to be detected contains a homologous recombination fragment shown in SEQ ID NO. 1.

In addition, in the method for detecting the recombinant nucleic acid fragment provided by the application, the primer combination for amplifying and detecting the sequence shown in SEQ ID NO. 2 is as follows: amplification primers, including a forward primer: 5'-TCATGCTCCCCATGATCTTGTT-3', and reverse primer: 5'-AATTATGTGCCTCCGTACCACC-3', respectively; sequencing primers, including a forward primer: 5'-TCATGCTCCCCATGATCTTGTT-3', forward primer: 5'-CGAGACTTG AAAGCCACAGA-3', and reverse primer: 5'-AATTATGTGCCTCCGTACCA CC-3' are provided. The method comprises the steps of taking genome DNA of a sample to be detected as a template, carrying out PCR amplification by using the amplification primer, sequencing an obtained amplification product by using the sequencing primer, and if a sequencing result is consistent with or complementary to a sequence of SEQ ID NO. 2, determining that the sample to be detected contains a homologous recombination fragment shown in SEQ ID NO. 2.

The recombinant nucleic acid fragment containing the sequence shown by SEQ ID NO. 1 and/or SEQ ID NO. 2 in the sample to be detected is determined through detection, so that the recombinant nucleic acid fragment containing the resistant genome in the sample to be detected can be determined.

In addition, the present application also provides a kit for detecting a recombinant nucleic acid fragment, which comprises the primer as described above.

Further, the present application also provides a method for screening rice plants or seeds containing the recombinant nucleic acid fragment, which comprises the step of detecting whether the genome of the rice plant to be detected contains the recombinant nucleic acid fragment as described above. In one embodiment, the primers described above are used to detect whether the genome of the rice plant to be tested contains the recombinant nucleic acid fragment as described above. In another embodiment, the method for detecting the recombinant nucleic acid fragment as described above is used to detect whether the genome of the rice plant to be detected contains the recombinant nucleic acid fragment as described above. In yet another embodiment, the kit as described above is used to detect whether the genome of the rice plant to be tested contains the recombinant nucleic acid fragment as described above.

In yet another aspect, the present application provides rice plants or seeds thereof selected by the methods comprising the recombinant nucleic acid fragments disclosed herein.

The method for breeding the rice plant containing the brown planthopper resistant genome recombinant nucleic acid fragment based on the whole genome selective breeding technology has the characteristics of rapidness, accuracy and stability. Only through the transformation of five generations, only the target genome segment can be introduced into the acceptor material, and the reversion of the background can be realized at the same time. The improved receptor material is a photo-thermo sensitive genic male sterile line 'dragon S'. By using the method, the brown planthopper resistant genome segment can be introduced on the premise of not changing the photo-thermo-sensitive genic male sterile characteristic of the dragon S. Furthermore, the resistance of the hybrid brown planthopper is greatly improved by matching. The recombinant nucleic acid fragment provided by the application is closely related to resistance of brown planthopper, and can be used as a resistance resource to be applied to cultivation of other varieties.

Drawings

FIG. 1 shows the results of the PCR 023411 RICE RICE60K whole genome breeding chip in example 1 of the present application; wherein, the boxes indicated by the abscissa number sequentially represent 12 rice chromosomes, the ordinate number is the physical position [ in megabases (Mb) ] on the rice genome, the gray line represents the acceptor parent 'LongS' genotype, the black line represents the donor parent 'Hua 130B' genotype, and the white line represents the same genotype of the two parents, i.e. no polymorphic segment. In the figure, the black circle of chromosome 4 shows that the section is the introduced anti-brown planthopper genome recombinant nucleic acid fragment RecCR 023411.

FIG. 2 shows the sequencing alignment of homologous recombination fragments upstream of RecCR023411 in example 2 of the present application; the asterisks shown in the figure represent the same bases in the alignment results, in the figure, CR023411 is the obtained new line, T007 is the acceptor parent 'dragon S', and R005 is the donor parent 'Hua 130B'.

FIG. 3 shows the sequencing alignment of homologous recombination fragments downstream of RecCR023411 in example 2 of the present application.

FIG. 4 is a diagram showing the structure of the homologous recombination fragment flanking RecCR023411 in example 2 of the present application; wherein (A) is the structure diagram of an upstream homologous recombination fragment; (B) the upper base is SNP or InDel mark of donor 'Hua 130B' and the lower base is SNP or InDel mark of acceptor 'LongS'. The grey segment is derived from the ` Long S ` genome segment, the black segment is derived from the ` Hua 130B ` genome segment, the white segment is the homologous recombination segment, the abscissa is the fragment length in base pair number (bp) units.

FIG. 5 shows the results of the indoor identification of resistance to brown planthopper by CR023411 in example 3 of the present application; the blades shown in the figure are in the order: (A) high-susceptibility brown planthopper variety 'taizhongzhongyuan No. 1'; (B) original variety 'dragon S'; (C) improved new strain CR 023411; (D) the donor parent, Hua 130B'.

Detailed Description

The following definitions and methods are provided to better define the present application and to guide those of ordinary skill in the art in the practice of the present application. Unless otherwise indicated, terms are to be understood in accordance with their ordinary usage by those of ordinary skill in the relevant art.

As used herein, "nucleotide sequence" includes reference to deoxyribonucleotide or ribonucleotide polymers in either single-or double-stranded form, and unless otherwise limited, nucleotide sequences are written in the 5 'to 3' direction from left to right, and include known analogs (e.g., peptide nucleic acids) having the basic properties of natural nucleotides that hybridize to single-stranded nucleic acids in a manner similar to naturally occurring nucleotides.

In some embodiments, changes may be made to the nucleotide sequences of the present application to make conservative amino acid substitutions. In certain embodiments, substitutions that do not alter the amino acid sequence of the nucleotide sequences of the present application can be made according to monocot codon preferences, e.g., codons encoding the same amino acid sequence can be substituted with monocot preferred codons without altering the amino acid sequence encoded by the nucleotide sequence.

In particular, the application relates to further optimization of the resulting nucleotide sequence of SEQ ID NO 1 or SEQ ID NO 2. More details of this method are described in Murray et al (1989) Nucleic Acids Res.17: 477-498. The optimized nucleotide sequence can be used for improving the expression of the brown planthopper resistant genome recombinant nucleic acid segment in rice.

In some embodiments, the present application also relates to variants of the sequence shown in SEQ ID NO. 1 or SEQ ID NO. 2. Generally, a variant of a particular nucleotide sequence will have at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 99.9% or more sequence identity, or the complement thereof, to the particular nucleotide sequence. Such variant sequences include additions, deletions or substitutions of one or more nucleic acid residues, which may result in the addition, removal or substitution of the corresponding amino acid residue. Sequence identity is determined by sequence alignment programs known in the art, including hybridization techniques. Nucleotide sequence variants of the embodiments may differ from the sequences of the present application by as little as 1-15 nucleotides, as little as 1-10 (e.g., 6-10), as little as 5, as little as 4, 3, 2, or even 1 nucleotide.

The application also relates to sequences comprising the specified positions in the sequences indicated under SEQ ID NO 1 or SEQ ID NO 2 or fragments or variants thereof or complements thereof, for example sequences comprising nucleotides 1274-773 of the sequences indicated under SEQ ID NO 1 or fragments or variants thereof or complements thereof or sequences 216-773 of the sequences indicated under SEQ ID NO 2. Based on the fragment containing the specific site, the corresponding sequence shown in SEQ ID NO. 1 or SEQ ID NO. 2 can be specifically identified. Furthermore, the recombinant nucleic acid fragment containing the resistance gene in the sample to be detected can be determined by identifying the recombinant nucleic acid fragment containing the sequence shown in SEQ ID NO. 1 or SEQ ID NO. 2.

As used herein, "rice" is any rice plant and includes all plant varieties that can be bred with rice. As used herein, "plant" or "plant" includes whole plants, plant cells, plant organs, plant protoplasts, plant cell tissue cultures from which plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants or plant parts, such as embryos, pollen, ovules, seeds, leaves, flowers, branches, fruits, stems, roots, root tips, anthers, and the like.

The method can be applied to any rice variety needing breeding. That is, any elite variety lacking a favorable trait (i.e., a variety having a good comprehensive trait and expected to have a future development) can be used as a recurrent parent. Another variety with advantageous traits that are lacking in the recipient is used as the donor parent. In an embodiment of the present application, the rice 'dragon S' was used as a recurrent parent, and the rice 'hua 130B' having good resistance to brown planthopper was used as a donor.

In the breeding method of the recombinant plant provided by the application, the molecular marker is used for carrying out prospect selection on the recombinant plant. The reliability of the foreground selection mainly depends on the closeness degree of linkage between the marker and the target genome segment, and in order to improve the accuracy of selection, the target genome segment is generally tracked and selected by two adjacent markers on two sides.

In an embodiment of the present application, the foreground selection marker used includes a positive selection marker and a negative selection marker, wherein the positive selection marker is a polymorphic molecular marker screened in the range of 50kb (the genetic distance of which is 0.2cM in rice) upstream and downstream from the target genome fragment (containing the brown planthopper resistance gene). The negative selection marker is a polymorphic molecular marker screened in the range of 500kb (genetic distance of 2cM in rice) upstream and downstream from the target genome fragment. In a specific embodiment, the positive selection marker used in the optimized screening is the marker BphC04ID06 closely linked to the target genomic fragment, the negative selection marker is the molecular marker RM6659 approximately 370kb upstream from the target fragment, and the molecular marker BphC04S08 approximately 200kb downstream from the target fragment.

In the present embodiment, when the detection of homologous recombination is carried out using the above-mentioned foreground selection marker, the criteria for judging one-sided or one-sided homologous recombination are that BphC04ID06 detects the same band pattern as ` Hua 130B ` and RM6659 or BphC04S08 detects the same band pattern as ` Dragon S `; the criteria for judging bilateral or bilateral homologous recombination were that BphC04ID06 detected the same band pattern as ` Hua 130B ` and RM6659 and BphC04S08 detected the same band pattern as ` Dragon S `.

In the present application, any available chip can be used for background selection in the breeding method provided in the present application. In a preferred embodiment, the RICE whole genome breeding chip RICE6K disclosed in the present applicant's Chinese patent application CN102747138A, or the RICE whole genome breeding chip RICE60K disclosed in PCT international application WO/2014/121419, can be used. The entire contents of both of these applications are incorporated herein by reference in their entirety.

The following examples are for the purpose of illustration only and are not intended to limit the scope of the present application. Unless otherwise indicated, the examples follow conventional experimental conditions, such as the Molecular cloning handbook, Sambrook et al (Sambrook J & Russell DW, Molecular cloning: a laboratory manual,2001), or the conditions suggested by the manufacturer's instructions.

The rice plant material information used in the application can be seen in Chinese rice varieties and pedigree databases thereof (http:// www.ricedata.cn/variety/index. htm).

The physical location of the rice genome referred to in this application is referred to the rice Nipponbare genome MSU/TIGR annotation, version 6.1 (http:// rice plant. MSU. edu /).

The published SSR molecular markers mentioned in the application can be seen in the website http:// www.gramene.org/.

Example 1Breeding recombinant plant with brown planthopper resistant genome segment

The materials used in this example were rice 'dragon S' and rice 'hua 130B'.

Rice 'Hua 130B' has good resistance to brown planthopper, and presumably it is the cluster regions of chromosome 4 Bph3(Liu et al, Nature Biotechnology.2015,33: 301-.

In the process of breeding the recombinant plants, the molecular markers are used for carrying out prospect selection on the recombinant plants, and the adopted prospect selection molecular markers are screened. The molecular marker used is partially derived from the website http:// www.gramene.org/, and partially designed by self. The design method is to download the segment DNA sequence with reference to the rice Nipponbare genome MSU/TIGR annotation version 6.1. SSR sites in the above sequences were scanned using SSRLOCATOR software. Primers are designed for the found SSR loci by using Primer Premier 3.0 software, and a Primer pair 106 is designed in total. The polymorphism of the primer pair in ` Hua 130B ` and ` Long S ` is screened by a PCR method, and finally, the foreground selective molecular markers which have polymorphism and high amplification efficiency in two materials are selected, namely a positive selective marker BphC04ID06, a negative selective marker RM6659 and a negative selective marker BphC04S 08.

The specific primer information for PCR amplification of the above molecular markers is shown in Table 1.

TABLE 1 Foreground selection of molecular marker primer information

The genome segment of the gene cluster in the 'Hua 130B' is introduced into the 'dragon S', and the specific process is as follows:

hybridizing the 'dragon S' as recurrent parent and 'Hua 130B' as donor parent, backcrossing the obtained hybrid with the recurrent parent 'dragon S' to obtain BC₁F₁After the seed is grown, the recombinant individual Plant is selected by positive selection marker BphC04ID06 and negative selection markers RM6659 and BphC04S08, 10 individuals which are homologously recombined at one side of the target genome fragment, namely BphC04ID06 detects the same band type as 'Hua 130B' and RM6659 or BphC04S08 detects the same band type as 'Long S', and the background selection is carried out by RICE whole genome breeding chip RICE6K (CN102747138A) (Yu et al, Plant Biotechnology journal.2014,12: 28-37).

Comparing the chip results in 10 selected unilaterally homologous recombinant individuals, selecting the recombinant individual with the best background recovery (the background recovery value of the generation exceeds 75%), backcrossing the recombinant individual with the receptor parent 'LongS', and obtaining BC₂F₁Seed, after seedling raising, using positive selection marker BphC04ID06 to make detection, selecting recombinant single plant containing target genome fragment, i.e. BphC04ID06 can detect that it has the same banding pattern as 'Hua 130B', and using rice whole genome breeding coreSheet RICE6K was background selected.

Selecting the single plant with better background recovery (the background recovery value of the generation exceeds 87.5 percent), and backcrossing the single plant with the recurrent parent 'LongS' again to obtain BC₃F₁And (3) after seedling raising, screening homologous recombination fragments on the other side of the target genome fragment on harvested seeds by using a positive selection marker BphC04ID06 and negative selection markers RM6659 and BphC04S08 to obtain 2 individuals recombined on two sides of the target fragment, namely BphC04ID06 detects the same banding pattern as 'Hua 130B', and RM6659 and BphC04S08 detect the same banding pattern as 'LongS'.

The 2 double-sided cross-over individuals were subjected to background and target fragment selection using a RICE whole genome breeding chip RICE60K (WO/2014/121419) (Chen et al, Molecular plant 2014,7: 541) 553, and one target individual with a smaller introduced target fragment and a good background was selected (the generation background recovery value was more than 93.75%).

Selfing the selected single plant once to obtain BC₃F₂After seedling raising, the positive selection marker BphC04ID06 is used for detecting the seedlings, a single plant containing a target genome fragment, namely BphC04ID06 is selected, the same banding pattern as 'Hua 130B' is detected, and the RICE whole genome breeding chip RICE60K is used for carrying out background selection on the single plant.

Finally, one strain which is homozygous for the target fragment and has a background recovery value (the background recovery value exceeds 99%) is obtained and named as CR 023411. The chip detection results are shown in FIG. 1.

Since the dragon S is a two-line sterile line, BC in the process₁F₁、BC₂F₁、BC₃F₁And BC₃F₂The selected individual plants in the generation are sterile individual plants, and the fertility transformation of the sterile individual plants is realized by adopting the following method for backcrossing or selfing: when the sterile single plant enters the reproductive stage 4, treating in a low-temperature treatment area (21-23 ℃) for about 10 days, and utilizing a plant artificial climate box, a plant growing chamber, a cold water irrigation pool and the like; and (3) carrying out fertility identification on the pollen of the extracted ear by using an iodine-potassium iodide dyeing method, judging that more than 70% of ears which can be bred by the pollen are fertility successfully transformed ears, and then carrying out backcross or selfing.

Example 2Determination of homologous recombination fragment after introduction of brown planthopper resistant genome fragment

In order to determine the size of the introduced genome fragment resisting the brown planthopper, the homozygous single strain of the genome fragment of the dragon S introduced with the brown planthopper is subjected to sequencing of homologous recombination fragments at both sides of the target genome fragment. The brown planthopper resistant genome recombinant nucleic acid fragment contained in CR023411 is named RecCR 023411.

As preliminarily determined by the detection result of a RICE whole genome breeding chip RICE60K, RecCR023411 is positioned between two SNP markers F0406623871GA and F0407163900 TC.

Meanwhile, Miseq sequencing technology was used to perform whole genome sequencing on three samples, dragon S, hua 130B and CR 023411. Library construction was performed using TruSeq Nano DNA LT Kit (illumina) Kit, Quantification was performed using Library Quantification Kit-Universal (KAPA biosystems) Kit, and sequencing was performed using MiSeq V2 Reagent Kit (illumina). Detection was performed using Miseq bench top sequencer (illumina). The specific steps and methods are shown in each kit and the instruction manual of the sequencer.

According to the SNP chip and the Miseq sequencing result, the upstream homologous recombination fragment of the CR023411 brown planthopper resistant genome recombination fragment is positioned in the interval from 6628628bp to 6630608bp of the 4 th chromosome, and the downstream homologous recombination fragment is positioned in the interval from 7155133bp to 7156125 bp.

On the basis, the DNA sequences of the corresponding segments were downloaded with reference to the rice Nipponbare genome MSU/TIGR annotation, version 6.1. Amplification and sequencing primers were designed using Primer Premier 5.0 software, with the design requirements being around 22nt Primer length, 40-60% GC content and no mismatches.

By taking the acceptor parent 'dragon S' and the donor parent 'Hua 130B' as controls, amplification primers are respectively designed for upstream and downstream homologous recombination fragments of CR023411, high fidelity enzyme KOD FXneo (TOYOBO) is used for amplification, and a two-step method or a three-step method is used for searching for the optimal amplification condition, so that the amplification product is ensured to be displayed as a single bright band in agarose gel electrophoresis detection. Wherein the reaction conditions of the upstream homologous recombination fragment amplification primers are as follows: 94 ℃ for 2 min; 10sec at 98 ℃, 30sec at 60 ℃, 90sec at 68 ℃, 37 cycles; 1min at 20 ℃. The reaction conditions of the downstream homologous recombination fragment amplification primer are as follows: 94 ℃ for 2 min; 10sec at 98 ℃, 150sec at 68 ℃, 37 cycles; 1min at 20 ℃. Thus, two pairs of amplification primers are finally screened for amplification of upstream and downstream homologous recombination fragments, respectively.

In addition, the amplification product is used as a template, sequencing is carried out by a Sanger sequencing method, and 4 sequencing primers and 3 sequencing primers are finally screened out according to the actual sequencing effect and are respectively used for sequencing the upstream homologous recombination fragment and the downstream homologous recombination fragment.

The specific amplification primer and sequencing primer sequences are shown in Table 2, and the sequencing results are shown in FIGS. 2 and 3.

The sequencing length of the homologous recombination fragment upstream of RecCR023411 is 1979bp (SEQ ID NO: 1). 1-1274bp is the genome segment of acceptor 'dragon S', and compared with donor 'Hua 130B', 6 SNPs exist. The 535bp segment of 1275-1809bp is a homologous recombination segment. 1810 + 1979bp is a donor genome fragment of 'Hua 130B', and compared with 'Long S', 3 SNPs exist.

The sequencing length of the homologous recombination fragment downstream of RecCR023411 is 994bp (SEQ ID NO: 2). 1-216bp is the genome segment of donor ` Hua 130B ` and there are 3 SNPs, 1 Indel, compared to ` Dragon S `. The 556bp segment, 772bp 217, is a homologous recombination segment. 773 994bp is the genome segment of the acceptor ' S, compared with the donor ' S130B ', there are 5 SNPs and 3 indels.

FIG. 4 shows a structural diagram of homologous recombination fragments flanking RecCR 023411. Wherein (A) is the structure diagram of an upstream homologous recombination fragment; (B) is a structure diagram of a downstream homologous recombination fragment. The upper base is SNP or InDel mark of donor 'Hua 130B', and the lower base is SNP or InDel mark of acceptor 'LongS'. Grey segments are derived from the 'dragon S' genome segment, black segments are derived from the 'hua 130B' genome segment, and white segments are homologous recombination segments. The abscissa is the fragment length in base pair number (bp).

TABLE 2 amplification and sequencing primer information for Brown planthopper resistant genomic recombinant nucleic acid fragments

Example 3Identification of resistance of 'Dragon S' after introduction of genome fragment of anti-brown planthopper

In order to identify the resistance of the selected plant containing the recombinant nucleic acid fragment to the brown planthopper, the indoor resistance identification of the brown planthopper is carried out on the new strain CR023411, the receptor parent 'dragon S', the donor parent 'Hua 130B' (as a positive control) and the high-susceptibility brown planthopper variety 'Taizhonghua No. 1' (as a negative control) which are selected and bred in the application, and the identification method is as follows.

Soaking and accelerating germination of each part of material indoors, then sowing the material in a plastic basin with scribed grid lines, sowing 45 plants in each part of material in 3 rows, and reserving 10 plants in each row for inoculation, wherein the total number of 30 plants with consistent healthy growth vigor are reserved when two leaves are in one heart period. The insects are sourced from brown planthoppers collected from fields and bred indoors. And (3) collecting 2-3-year nymphs to plants to be identified, wherein each plant is only provided with 5-10 nymphs. When 95% of the number 1 'dead seedlings in the' Taiwan stand begin to record the resistance grade of each identified seedling, the average value of the resistance grades of 30 seedlings is taken as the resistance grade of the material, and the resistance level is evaluated according to the resistance grade. Wherein, the resistance grade is 10 grades in total: stage 0 or 1, the blade is not damaged or the tip of the first blade is yellow; grade 2, first leaf 1/2 yellow or tip crinkled; grade 3, the first leaf becomes yellow or withered; at grade 4, the second leaf part or the apex of heart leaf becomes yellow; grade 5, the second leaf is yellow, shriveled or withered, and the heart leaves are green and curled; grade 6, curling heart leaves and withering heart leaf tips; grade 7, heart leaves are curled and withered, and plants are not dead; grade 8, withered heart leaves, slightly lodging; grade 9, lodging the whole plant. According to the resistance grades, the grade 0-0.9 is judged as high resistance, the grade 1.0-2.9 is resistance, the grade 3.0-5.9 is medium resistance, the grade 6.0-6.9 is medium feeling, the grade 7.0-7.9 is medium feeling, and the grade 8.0-9.0 is high feeling.

The results of identifying the indoor resistance of the brown planthopper are shown in a figure 5, wherein the 'Zhonghua No. 1' in the station is high-sensitive, the original variety 'LongS' is sensitive, the improved new strain CR023411 is resistant, and the donor parent 'Hua 130B' is high-resistant.

Although the present application has been described in detail with respect to the general description and specific embodiments, it will be apparent to those skilled in the art that certain modifications or improvements may be made based on the present application. Accordingly, such modifications and improvements are intended to be within the scope of this invention as claimed.

Claims (9)

1. A recombinant nucleic acid fragment consisting of a first recombinant nucleic acid fragment and a second recombinant nucleic acid fragment of:

-a first recombinant nucleic acid fragment being the sequence of SEQ ID No. 1 or the complement thereof;

-a second recombinant nucleic acid fragment which is the sequence of SEQ ID No. 2 or the complement thereof.

2. The primer set for detecting the fragments of claim 1, wherein the primer set consists of the following primers for detecting the first recombinant nucleic acid fragment and the second recombinant nucleic acid fragment:

-a primer for detecting the first recombined nucleic acid fragment, selected from the group consisting of:

(I) a forward primer which specifically recognizes the sequence of nucleotides 1 to 1274 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 1810-1979 of the sequence shown in SEQ ID NO. 1;

(II) a combination of a first set of primer pairs and a second set of primer pairs comprising

(a) The first set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 1 to 1274 of the sequence shown by SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 1275 and 1809 of the sequence shown by SEQ ID NO. 1; and

(b) a second set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 1275-1809 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 1810-1979 of the sequence shown in SEQ ID NO. 1;

-a primer for detecting the second recombinant nucleic acid fragment selected from the group consisting of:

(III) a forward primer which specifically recognizes the sequence of nucleotides 1 to 216 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 773-994 of the sequence shown by SEQ ID NO. 2;

(VI) the following combination of a third set of primer pairs and a fourth set of primer pairs, comprising

(c) Third set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 1 to 216 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 217 and 772 of the sequence shown by SEQ ID NO. 2; and

(d) a fourth set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 217-772 of the sequence shown in SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 773-994 of the sequence shown in SEQ ID NO. 2.

3. A primer set for detecting the fragment of claim 1, wherein the primer set is:

(I) primer pair for amplifying sequence shown in SEQ ID NO. 1

5’-AATAGTCCGACCTGGAATGAAAT-3’，

5’-TCTTTCGAGCGGATCTAATGC-3’；

(II) primer for sequencing sequence shown in SEQ ID NO. 1

5’-AATAGTCCGACCTGGAATGAAAT-3’；

5’-ACCGCTTCCCTATCCTATTT-3’；

5’-CTGTGATTTGCTATGGGTAA-3’；

5’-TCTTTCGAGCGGATCTAATGC-3’；

(III) primer pairs for amplifying sequences shown in SEQ ID NO. 2

5’-TCATGCTCCCCATGATCTTGTT-3’，

5'-AATTATGTGCCTCCGTACCACC-3', respectively; and

(IV) primer for sequencing SEQ ID NO. 2

5’-TCATGCTCCCCATGATCTTGTT-3’；

5’-CGAGACTTGAAAGCCACAGA-3’；

5’-AATTATGTGCCTCCGTACCACC-3’。

4. A method for detecting the recombinant nucleic acid fragment of claim 1, which comprises the steps of performing a PCR reaction using the primer set of claim 2 or 3 and a test genome as a template, and analyzing the amplification product.

5. A kit for detecting the recombinant nucleic acid fragment of claim 1, comprising the primer set of claim 2 or 3.

6. A method of screening rice plants or seeds containing the recombinant nucleic acid fragment of claim 1, comprising the step of detecting whether the genome of a test rice plant or seed contains the recombinant nucleic acid fragment of claim 1.

7. The method of claim 6, wherein the primer set of claim 2 or 3 is used to detect whether the genome of the rice plant or seed to be tested contains the recombinant nucleic acid fragment of claim 1.

8. The method of claim 6, wherein the method of claim 4 is used to detect whether the genome of a test rice plant or seed contains the recombinant nucleic acid fragment of claim 1.

9. The method of claim 6, wherein the kit of claim 5 is used to detect whether the genome of a test rice plant or seed contains the recombinant nucleic acid fragment of claim 1.

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