CN106609278B - Recombinant nucleic acid fragment RecCR020141 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 RecCR020141 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 the recombinant nucleic acid fragment bred by using a whole genome selective breeding technology, the recombinant nucleic acid fragment obtained by the breeding technology and a detection method thereof.

Background

Nilaparvata lugens, school name

Belonging to the order Homoptera, the family Pediculidae. 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 the phenotypic identification of brown planthoppers, the individual genes Bph14, Bph26 and Bph3, etc., have only been cloned 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 3300-5475 of the sequence 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 163-288 of the sequence depicted in SEQ ID NO 2 or a fragment or variant or complement thereof; 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 for specifically recognizing the sequence of nucleotides 1 to 3300 of the sequence shown in SEQ ID NO. 1 and a reverse primer for specifically recognizing the sequence of nucleotides 5475-5985 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 3300 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 3301-5474 of the sequence shown in SEQ ID NO. 1; and (b) a second set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 3301-5474 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 5475-5985 of the sequence shown in SEQ ID NO. 1; (III) a forward primer specifically recognizing a sequence comprising nucleotides 3300-3301 of the sequence shown in SEQ ID NO. 1 and a reverse primer specifically recognizing a sequence comprising nucleotides 5474-5475 of the sequence shown in SEQ ID NO. 1; (IV) a forward primer specifically recognizing the sequence comprising nucleotides 3300-3301 of the sequence shown in SEQ ID NO. 1 and a reverse primer specifically recognizing the sequence of nucleotides 5475-5985 of the sequence shown in SEQ ID NO. 1; (V) a forward primer which specifically recognizes a sequence of nucleotides 1 to 3300 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes a sequence comprising nucleotides 5474 and 5475 of the sequence shown in SEQ ID NO. 1; and/or optionally, (VI) a forward primer which specifically recognizes the sequence of nucleotides 1 to 163 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 288 and 907 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 163 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 164-287 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 164-287 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 288-907 of the sequence shown by SEQ ID NO. 2; (VIII) a forward primer specifically recognizing a sequence comprising nucleotides 163-164 of the sequence indicated by SEQ ID NO:2 and a reverse primer specifically recognizing a sequence comprising nucleotides 287-288 of the sequence indicated by SEQ ID NO: 2; (IX) a forward primer which specifically recognizes a sequence comprising nucleotides 163-164 of the sequence shown by SEQ ID NO:2 and a reverse primer which specifically recognizes a sequence comprising nucleotides 288-907 of the sequence shown by SEQ ID NO: 2; (X) a forward primer which specifically recognizes the sequence of nucleotides 1 to 163 of the sequence shown by SEQ ID NO:2 and a reverse primer which specifically recognizes the sequence comprising nucleotides 287 and 288 of the sequence shown by SEQ ID NO: 2.

In one embodiment, the primer pair used to amplify the sequence shown in SEQ ID NO. 1 is, for example, 5'-TATAAGCATTGGTCAGGCCACC-3', 5'-ATAAGCCCCAACTGCAAGCATC-3'; 5'-ATACCGATTGAAGAACCTCTAACTG-3', 5'-ATGTTTAAGTTTGTGGGTATGAGTT-3', respectively; and 5'-TTTTGGACGATATGCCCCTAATTGA-3', 5'-CTGACATGGCTGGAGATGTTGACAC-3'. Sequencing primers for detecting the sequence shown in SEQ ID NO. 1 are, for example, 5'-GGAGTATTTGGGAGTCTGG-3'; 5'-TTTGGCTAGTCATCCTGTA-3', respectively; 5'-GCCGCATGTCACGATGTCT-3', respectively; 5'-TCACTTTGATCCGACTCTT-3', respectively; 5'-ATAAGCCCCAACTGCAAGCATC-3', respectively; 5'-ATACCGATTGAAGAACCTCTAACTG-3', respectively; 5'-TGAGGCAAGAATGGCAGAAT-3', respectively; 5'-GAGGACGGTGAACCAGTAGC-3', respectively; 5'-AACCCAAGCCAGAAGCGGAA-3', respectively; 5'-CCCAAGCCAGAAGCGGAAGA-3', respectively; 5'-GTCGTAGGCGTCGGTGAAGA-3', respectively; and 5'-ATGTTTAAGTTTGTGGGTATGAGTT-3'.

In another embodiment, the primer pair used to amplify the sequence shown in SEQ ID NO. 2 is, for example, 5'-GTCCCTGCACCGTCTCCTACACT-3', 5'-ACTCCACAGACCTCTATCCCATC-3'. The sequencing primers used to detect the sequence shown in SEQ ID NO. 2 are, for example, 5'-GGTCGTTACGCAAGATTGA-3'; and 5'-CTCACAAGGCCACAGGTATG-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 rice 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 MS 5; 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 single-side homologous recombination fragment screening on brown planthopper resistant genome fragments by using a positive selection marker BphC04ID06, a negative selection marker RM6659 and MS5, 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) carrying out backcross again on the selected recombinant single plant with good background recovery (the background recovery value of the generation exceeds 87.5 percent) and the recurrent parent to obtain three backcross generations, carrying out screening on homologous recombination fragments on the other side of the brown planthopper resistant genome fragment by utilizing a positive selection marker BphC04ID06, a negative selection marker RM6659 and MS5, 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'-TGTGGAGGCTTAGGAAATTCTGG-3', and the reverse primer is 5'-TGTGAAACATGCCACGATACTGC-3'; the primer pair for amplifying the molecular marker MS5, wherein the forward primer is 5'-TTGTGGGTCCTCATCTCCTC-3', and the reverse primer is 5'-TGACAACTTGTGCAAGATCA-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'-TATAAGCATTGGTCAGGCCACC-3', reverse primer: 5'-ATAAGCCCCAACTGCAAGCATC-3', respectively; a forward primer: 5'-ATACCGATTGAAGAACCTCTAACTG-3', reverse primer: 5'-ATGTTTAAGTTTGTGGGTATGAGTT-3', respectively; and a forward primer: 5'-TTTTGGACGATATGCCCCTAATTGA-3', reverse primer: 5'-CTGACATGGCTGGAGATGTTGACAC-3', respectively; sequencing primers, including a forward primer: 5'-GGAGTATTTGGGAGTCTGG-3', forward primer: 5'-TTTGGCTAGTCATCCTGTA-3', reverse primer: 5'-GCCGCATGTCACGATGTCT-3', forward primer: 5'-TCACTTTGATCCGACTCTT-3', reverse primer: 5'-ATAAGCCCCAACTGCAAGCATC-3', forward primer: 5'-ATACCGATTGAAGAACCTCTAACTG-3', reverse primer: 5'-TGAGGCAAGAATGGCAGAAT-3', reverse primer: 5'-GAGGACGGTGAACCAGTAGC-3', reverse primer: 5'-AACCCAAGCCAGAAGCGGAA-3', forward primer: 5'-CCCAAGCCAGAAGCGGAAGA-3', reverse primer: 5'-GTCGTAGGCGTCGGTGAAGA-3', and reverse primer: 5'-ATGTTTAAGTTTGTGGGTATGAGTT-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'-GTCCCTGCACCGTCTCCTACACT-3', reverse primer: 5'-ACTCCACAGACCTCTATCCCATC-3', respectively; sequencing primers, including a forward primer: 5'-GGTCGTTACGCAAGATTGA-3', and reverse primer: 5'-CTCACAAGGCCACAGGTATG-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 resistance gene 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 'flourishing B', is a maintainer line of a high-quality early indica sterile line 'flourishing A', and has the outstanding characteristic of good rice quality. By using the method, under the condition of keeping the original advantages of 'heyday B', the brown planthopper resistant genome fragment can be introduced, so that the brown planthopper resistance of the brown planthopper is improved. Further, stable 'flourishing A' containing brown planthopper resistant fragments can be obtained through at least one generation of hybridization and one generation of backcross, and the resistance of the hybrid brown planthopper is greatly improved through 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 detection of the CR020141 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 'flourishing B' genotype, the black line represents the donor parent 'Hua 2048B' genotype, and the white line represents the same genotype of the two parents, i.e. no polymorphism segment. The black circle of chromosome 4 shows the section of the recombinant nucleic acid fragment RecCR020141 of the introduced brown planthopper-resistant genome.

FIGS. 2A, 2B and 2C are the sequencing alignment results of the upstream homologous recombination fragment RecCR020141 in example 2 of the present application; the asterisks shown in the figure represent the same bases in the alignment results, in the figure, CR020141 is the new strain obtained, T003 is the acceptor parent 'ShengshiB', and R006 is the donor parent 'Hua 2048B'.

FIG. 3 shows the sequencing alignment of the homologous recombinant fragment downstream of RecCR020141 in example 2 of the present application.

FIG. 4 is a structural diagram of homologous recombination fragments flanking RecCR020141 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 'Hua2048B' and the lower base is SNP or InDel mark of acceptor 'ShengShi B'. The grey segment is derived from the 'flourishing B' genome segment, the black segment is derived from the 'Hua 2048B' genome segment, the white segment is the homologous recombination segment, the abscissa is the segment length, and the unit is the number of base pairs (bp).

FIG. 5 shows the results of indoor identification of resistance to CR020141 brown planthopper 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 'flourishing B'; (C) the improved new strain CR 020141; (D) the donor parent, hua 2048B.

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 sites in the sequences indicated under SEQ ID NO 1 or SEQ ID NO 2 or fragments or variants or complements thereof, for example sequences comprising nucleotides 3300-5475 of the sequence indicated under SEQ ID NO 1 or fragments or variants or complements thereof, or sequences comprising nucleotides 163-288 of the sequence indicated under SEQ ID NO 2 or fragments or variants or complements thereof. 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 tested 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, rice 'heyday B' was used as a recurrent parent, and rice 'hua 2048B' 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 foreground selectable marker used in the optimized screening is the marker BphC04ID06 that is closely linked to the target genomic fragment, the negative selectable marker is the molecular marker RM6659 that is about 220kb upstream from the target fragment, and the molecular marker MS5 that is about 450kb 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 ` Hua2048B ` and RM6659 or MS5 detects the same band pattern as ` ShengshiB `; the criteria for the bilateral or bilateral homologous recombination were that BphC04ID06 detected the same band pattern as ` Hua2048B ` and RM6659 and MS5 detected the same band pattern as ` ShengshiB `.

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 Manual, 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 'heyday B' and rice 'hua 2048B'.

Rice 'Hua 2048B' has good resistance to brown planthopper, and presumably is a gene cluster region 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 2048B ` and ` Shengshi B ` is screened by a PCR method, and finally, a foreground selective molecular marker which has polymorphism and high amplification efficiency in two materials is selected, wherein the foreground selective molecular marker is positive selective marker BphC04ID06, negative selective marker RM6659 and MS 5. 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 'Hua2048B' is introduced into the 'ShengShi B', and the specific process is as follows:

hybridizing 'flourishing B' as recurrent parent 'Hua2048B' as donor parent, backcrossing the obtained hybrid with recurrent parent 'flourishing B' to obtain BC₁F₁Seeds, after growing seedlings, were selected for recombinant individuals using positive selection marker BphC04ID06 and negative selection markers RM6659, MS5, 9 individuals that were homologously recombinant on one side of the target genomic fragment, that is, BphC04ID06, were selected for the same banding pattern as ` Hua2048B ` and RM6659 or MS5 were selected for the same banding pattern as ` ShengshiB `, and were background selected using RICE whole genome breeding chip RICE6K (CN102747138A) (Yu et al, plant Biotechnology journal.2014,12: 28-37).

Comparing the chip results in 9 selected single-side homologous recombinant single plants, selecting the recombinant single plant with best background recovery (the background recovery value of the generation exceeds 75%), backcrossing the recombinant single plant with recurrent parent 'heyday B' again to obtain BC₂F₁After the seeds are raised, the forward selection marker BphC04ID06 is used for detecting the seeds, a recombinant single plant containing a target genome fragment, namely BphC04ID06 is selected, the banding pattern of the recombinant single plant is the same as that of 'Hua2048B', and the RICE whole genome breeding chip RICE6K is used for carrying out background selection on the recombinant single plant.

Selecting 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 'flourishing B' again to obtain BC₃F₁And (3) screening homologous recombination fragments on the other side of the target genome fragment of the harvested seeds by using a positive selection marker BphC04ID06, a negative selection marker RM6659 and an MS5 after seedling raising of the seeds to obtain 9 individuals recombined on two sides of the target fragment, namely BphC04ID06 detects the same banding pattern as 'Hua 2048B', and RM6659 and MS5 detect the same banding pattern as 'Shengshi B'.

The 9 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 that of 'Hua2048B' 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 segment and has a recovered background (the background recovery value exceeds 99%) is obtained and named as CR 020141. The chip detection results are shown in FIG. 1.

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

To determine the size of the introduced brown planthopper resistant genomic fragment, the homozygous individual for the ` Severe B ` introduced fragment was sequenced for homologous recombination fragments flanking the target genomic fragment. The brown planthopper resistant genome recombinant nucleic acid fragment contained in CR020141 is named RecCR 020141.

The RecCR020141 is located between two SNP markers F0405799769TC and F0407038360TG as preliminarily determined by the detection result of a RICE whole genome breeding chip RICE 60K.

Meanwhile, Miseq sequencing technology was used to perform whole genome sequencing on three samples, named 'heyday B', 'hua 2048B' and CR 020141. Library construction was performed using TruSeq Nano DNA LT Kit (illumina) Kit, quantification was performed using LibraryQuantification Kit-Universal (KAPA biosystems) Kit, and sequencing was performed using MiSeq V2Reagent Kit (illumina) Kit. 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 CR020141 brown planthopper resistant genome recombination fragment is positioned in the interval of 5803348bp to 5809336bp of the 4 th chromosome, and the downstream homologous recombination fragment is positioned in the interval of 7015808bp to 7016712 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.

And (2) respectively designing amplification primers for upstream and downstream homologous recombination fragments of CR020141 by taking an acceptor parent 'flourishing B' and a donor parent 'Hua2048B' as controls, amplifying by using a high-fidelity enzyme KOD FXneo (TOYOBO), and searching for an optimal amplification condition by using a two-step method or a three-step method to ensure that an amplification product shows 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; 98 ℃ 10sec, 61 ℃ 30sec, 68 ℃ 150sec, 37 cycles; 1min at 20 ℃. The reaction conditions of the downstream homologous recombination fragment amplification primer are as follows: 94 ℃ for 2 min; 98 ℃ 10sec, 61 ℃ 30sec, 68 ℃ 150sec, 37 cycles; 1min at 20 ℃. Thus, three pairs of amplification primers are finally screened for amplification of the upstream homologous recombination fragment, and one pair of primers is screened for amplification of the downstream homologous recombination fragment.

In addition, the amplification product is used as a template, sequencing is carried out by a Sanger sequencing method, and 12 sequencing primers and 2 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. Specific amplification primer and sequencing primer sequences are shown in Table 2, and sequencing results are shown in FIG. 2A, FIG. 2B, FIG. 2C and FIG. 3.

The sequencing length of the homologous recombination fragment upstream of RecCR020141 is 5985bp (SEQ ID NO: 1). 1-3300bp is the recipient's genome segment of flourishing B', compared with donor 'Hua 2048B', there are 2 SNPs, 1 InDel. The 2174bp segment of 3301-5474bp is a homologous recombination segment. 5475-5985bp is a donor genome fragment of 'Hua 2048B', and compared with 'ShengShi B', 2 SNPs and 1 InDel exist.

The sequencing length of the homologous recombination fragment downstream of RecCR020141 was 907bp (SEQ ID NO: 2). 1-163bp is the genome segment of donor 'Hua 2048B', and there are 9 SNPs compared with 'ShengShi B'. The 124bp segment of 164-287bp was the homologous recombination segment. 288-907bp is the genome segment of the acceptor 'ShengshiB', and compared with the donor 'Hua2048B', there are 9 SNPs and 2 indels.

FIG. 4 shows the structure of homologous recombination fragments flanking RecCR 020141. 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 marker of donor 'Hua 2048B', and the lower base is SNP or InDel marker of acceptor 'ShengShi B'. The grey segment is derived from 'flourishing B' genome segment, the black segment is derived from 'Hua 2048B' genome segment, and the white segment is a homologous recombination segment. The abscissa is the fragment length in base pair number (bp).

TABLE 2 amplification and sequencing primer information for recombinant nucleic acid fragments of rice blast resistant genomes

Example 3Identification of resistance after introduction of genome fragment of brown planthopper resistance in' flourishing B

In order to identify the resistance effect, the indoor resistance identification of the brown planthopper is carried out on the new strain CR020141 bred by the application, the receptor parent 'flourishing B', the donor parent 'Hua 2048B' (as a positive control) and the high-susceptibility brown planthopper variety 'Taizhonghua No. 1' (as a negative control), 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 resistance in brown planthopper chambers are shown in figure 5, wherein the 'Taizhongyuan No. 1' is high-sensitive, the original variety 'flourishing B' is sensitive, the improved new strain CR020141 is resistant, and the donor parent 'Hua 2048B' 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/or a second recombinant nucleic acid fragment selected from the group consisting of:

-a first recombinant nucleic acid fragment selected from the group consisting of:

i) 1 or the complementary sequence thereof of nucleotides 3300-5475 of the sequence shown in SEQ ID NO;

ii) the sequence shown in SEQ ID NO. 1 or the complementary sequence thereof;

-a second recombinant nucleic acid fragment selected from:

iii) the sequence of nucleotide 163-288 of the sequence indicated in SEQ ID NO. 2 or a complementary sequence thereof;

iv) the sequence shown in SEQ ID NO. 2 or the complementary sequence thereof.

2. The primer for detecting the fragment of claim 1, wherein the primer is selected from the group consisting of a primer for detecting a first recombinant nucleic acid fragment and/or a primer for detecting a 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 3300 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 5475-5985 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 3300 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 3301-5474 of the sequence shown in SEQ ID NO. 1; and

(b) a second set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 3301-5474 of the sequence shown in SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence of nucleotides 5475-5985 of the sequence shown in SEQ ID NO. 1;

(III) a forward primer which specifically recognizes the sequence comprising nucleotides 3300-3301 of the sequence shown by SEQ ID NO:1 in the sequence shown by SEQ ID NO:1 and a reverse primer which specifically recognizes the sequence comprising nucleotides 5474-5475 of the sequence shown by SEQ ID NO:1 in the sequence shown by SEQ ID NO: 1;

(IV) a forward primer specifically recognizing the sequence comprising nucleotides 3300-3301 of the sequence shown by SEQ ID NO. 1 and a reverse primer specifically recognizing the sequence comprising nucleotides 5475-5985 of the sequence shown by SEQ ID NO. 1 in the sequence shown by SEQ ID NO. 1; or

(V) a forward primer which specifically recognizes the sequence of nucleotides 1 to 3300 of the sequence shown by SEQ ID NO. 1 and a reverse primer which specifically recognizes the sequence comprising nucleotides 5474 and 5475 of the sequence shown by SEQ ID NO. 1; -a primer for detecting the second recombinant nucleic acid fragment selected from the group consisting of:

(VI) a forward primer which specifically recognizes the sequence of nucleotides 1 to 163 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 288 and 907 of the sequence shown by SEQ ID NO. 2;

(VII) the following combination of a third group of primer pairs and a fourth group of primer pairs, which comprises

(c) Third set of primer pairs: a forward primer which specifically recognizes the sequence of nucleotides 1 to 163 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 164-287 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 164-287 of the sequence shown by SEQ ID NO. 2 and a reverse primer which specifically recognizes the sequence of nucleotides 288-907 of the sequence shown by SEQ ID NO. 2;

(VIII) a forward primer which specifically recognizes the sequence of SEQ ID NO:2 comprising nucleotides 163-164 of the sequence of SEQ ID NO:2 and a reverse primer which specifically recognizes the sequence of SEQ ID NO:2 comprising nucleotides 287-288 of the sequence of SEQ ID NO: 2;

(IX) a forward primer which specifically recognizes the sequence of nucleotides 163-164 of the sequence shown by SEQ ID NO:2 and a reverse primer which specifically recognizes the sequence of nucleotides 288-907 of the sequence shown by SEQ ID NO: 2;

(X) a forward primer which specifically recognizes the sequence of nucleotides 1 to 163 of the sequence shown by SEQ ID NO:2 and a reverse primer which specifically recognizes the sequence comprising nucleotides 287 and 288 of the sequence shown by SEQ ID NO:2 among the sequences shown by SEQ ID NO: 2.

3. A primer for detecting the fragment of claim 1, wherein the primer is selected from the group consisting of:

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

5’-TATAAGCATTGGTCAGGCCACC-3’，

5’-ATAAGCCCCAACTGCAAGCATC-3’；

5’-ATACCGATTGAAGAACCTCTAACTG-3’，

5’-ATGTTTAAGTTTGTGGGTATGAGTT-3’；

5’-TTTTGGACGATATGCCCCTAATTGA-3’，

5’-CTGACATGGCTGGAGATGTTGACAC-3’；

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

5’-GGAGTATTTGGGAGTCTGG-3’；

5’-TTTGGCTAGTCATCCTGTA-3’；

5’-GCCGCATGTCACGATGTCT-3’；

5’-TCACTTTGATCCGACTCTT-3’；

5’-ATAAGCCCCAACTGCAAGCATC-3’；

5’-ATACCGATTGAAGAACCTCTAACTG-3’；

5’-TGAGGCAAGAATGGCAGAAT-3’；

5’-GAGGACGGTGAACCAGTAGC-3’；

5’-AACCCAAGCCAGAAGCGGAA-3’；

5’-CCCAAGCCAGAAGCGGAAGA-3’；

5’-GTCGTAGGCGTCGGTGAAGA-3’；

5’-ATGTTTAAGTTTGTGGGTATGAGTT-3’；

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

5’-GTCCCTGCACCGTCTCCTACACT-3’，

5’-ACTCCACAGACCTCTATCCCATC-3’；

(IV) primer for sequencing SEQ ID NO. 2

5’-GGTCGTTACGCAAGATTGA-3’；

5’-CTCACAAGGCCACAGGTATG-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 of claim 2 or 3 and a test genome as a template, and analyzing the PCR product.

5. A kit for detecting the recombinant nucleic acid fragment of claim 1, comprising the primer 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 primers of claim 2 or 3 are used to detect whether the genome of a test rice plant or seed 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.

Images