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Title:
RICE BROWN PLANTHOPPER RESISTANCE GENE BPH9 AND MOLECULAR MARKERS, AND USES THEREOF
Document Type and Number:
WIPO Patent Application WO/2014/036946
Kind Code:
A1
Abstract:
The present invention provides a rice brown planthopper resistance gene bph9 which has a nucleotide sequence shown as SEQ ID NO: 1 and a cDNA sequence shown as SEQ ID NO: 2, and the encoding protein and use thereof. The present invention also provides molecular markers of bph9 and use of the markers for screening brown planthopper resistance.

Inventors:
HE GUANGCUN (CN)
CHEN RONGZHI (CN)
WANG YANG (CN)
JING SHENGLI (CN)
ZHU LILI (CN)
DU BO (CN)
Application Number:
PCT/CN2013/082955
Publication Date:
March 13, 2014
Filing Date:
September 04, 2013
Export Citation:
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Assignee:
UNIV WUHAN (CN)
International Classes:
C12N15/29; C07K14/415; C12N1/21; C12N5/10; C12N15/11; C12N15/63; C12N15/82; C12N15/84; C12Q1/68
Foreign References:
CN101463354A2009-06-24
Other References:
HSU J.H. ET AL.: "Establishing the Platform of Polymorphic Markers for Rice", CROP, ENVIRONMENT & BIOINFORMATICS, vol. 9, no. 3, 1 September 2012 (2012-09-01), pages 137 - 159
MURAI, H ET AL.: "Constructing linkage maps of brown planthopper resistance genes bph1, bph2, 263 and bph9 on rice chromosome 12", ADVANCES IN RICE GENETICS, 2003, pages 263 - 265
Attorney, Agent or Firm:
LIU, SHEN & ASSOCIATES (Huibin BuildingNo.8 Beichen Dong Street, Chaoyang District, Beijing 1, CN)
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Claims:
CLAIMS

1. An isolated polynucleotide, having the sequence of a rice brown planthopper resistance gene Bph9, wherein said sequence is a nucleotide sequence shown as SEQ ID NO: 1, or a nucleotide sequence formed by the substitution, deletion or insertion of one or more nucleotides in SEQ ID NO: 1 and encoding an amino acid sequence which is the same or similar and has the same function.

2. An isolated polynucleotide, having a cDNA sequence of a rice brown planthopper resistance gene Bph9, wherein said sequence is a nucleotide sequence shown as SEQ ID NO: 2, or a nucleotide sequence formed by the substitution, deletion or insertion of one or more nucleotides in SEQ ID NO: 2 and encoding an amino acid sequence which is the same or similar and has the same function.

3. The polynucleotide of claim 2, the cDNA sequence thereof being shown as SEQ ID NO: 2.

4. A protein encoded by the polynucleotide of any one of claims 1 to 3.

5. The protein of claim 4, having an amino acid sequence shown as SEQ ID NO: 3.

6. A vector containing the polynucleotide of claims 1 to 3.

7. A host containing the vector of claim 6.

8. Use of the polynucleotide of any one of claims 1 to 3 in selective breeding of rice.

9. Use of the polynucleotide of any one of claims 1 to 3 in improving rice resistance to brown planthopper.

10. Use of the polynucleotide of any one of claims 1 to 3 in producing transgenic brown planthopper-resistant rice.

11. Molecular markers of the rice brown planthopper resistance gene Bph9, obtained by PCR using one of the following primer pairs: 1) marker primers, RM28438 marker primers:

forward primer sequence S -GTTCGTGAGCCACAACAAATCC^ (SEQ ID NO:4) reverse primer sequence S -GTTAAATGCTCCACCAAACACACC^ (SEQ ID NO:5),

2) marker primers, InD28450 marker primers:

forward primer sequence 5 Λ -GGTTGGAAAAGAAGCGATC A-3 Λ (SEQ ID NO:6) reverse primer sequence S -GCATCRTAAGGTTGCCATCA^ (SEQ ID NO:7),

3) marker primers, InD28453 marker primers:

forward primer sequence 5 Λ -GGCAAAGACAAGCCATAAGC-3 Λ (SEQ ID NO: 8) reverse primer sequence S -ATCCATCAGCAATGACACGA^ (SEQ ID NO:9),

4) marker primers, InD28432 marker primers:

forward primer sequence S -TGCAGACACCACATGCATAA^ (SEQ ID NO: 10) reverse primer sequence S -ACGCATACACACAGGGACAA^ (SEQ ID NO: 11),

5) marker primers, InD2 marker primers:

forward primer sequence S -AACAGACACGTTGCGTCTTG^ (SEQ ID NO: 12) reverse primer sequence S -CTTGCCGCTTAGAGGAGATG^ (SEQ ID NO: 13),

6) marker primers, InD 14 marker primers :

forward primer sequence S -CCACTCTGAAAATCCCAAGC^ (SEQ ID NO: 14) reverse primer sequence S -ACCAGTTAAGTCACGCTCAAA^ (SEQ ID NO: 15),

7) marker primers, RM28466 marker primers:

forward primer sequence 5 Λ -CCGACGAAGAAGACGAGG AGTAGCC-3 Λ (SEQ ID NO: 16)

reverse primer sequence S -AGGCCGGAGAGCAATCATGTCG^ (SEQ ID NO: 17),

8) marker primers, RM28481 marker primers:

forward primer sequence S -GTCAATTAACCATTGCCCATGC^ (SEQ ID NO: 18) reverse primer sequence S -TTCACGTGGGAACTACTCATGC^ (SEQ ID NO: 19),

9) marker primers, RM28486 marker primers:

forward primer sequence 5,-TTCTCTGAATGCCCTGTCTCTCC-3, (SEQ ID NO:20) reverse primer sequence S -GGCAAATCAGAACAAGTCTCACC^ (SEQ ID NO:21),

12. The molecular markers of claim 11 , further comprising being obtained by PCR using primers of InDel molecular marker IR2, the IR2 marker primers being:

forward primer sequence 5 Λ - AGGATGGGGAGAAGAAGACG-3 Λ (SEQ ID NO:22) reverse primer sequence S -GTGTTCCTTGTCGGGTGTA^ (SEQ ID NO:23).

Use of the molecular markers of claim 12 in selective breeding of brown planthopper-resistant

14. A molecular marker method for the rice brown planthopper resistance gene bph9, including amplifying a rice genomic DNA to be detected by using one of the following primer pairs, and detecting the product of amplification:

1) marker primers, RM28438 marker primers:

forward primer sequence S -GTTCGTGAGCCACAACAAATCC^ (SEQ ID NO:4) reverse primer sequence S -GTTAAATGCTCCACCAAACACACC^ (SEQ ID NO:5),

2) marker primers, InD28450 marker primers:

forward primer sequence 5 Λ -GGTTGGAAAAGAAGCGATC A-3 Λ (SEQ ID NO:6) reverse primer sequence S -GCATCRTAAGGTTGCCATCA^ (SEQ ID NO:7),

3) marker primers, InD28453 marker primers:

forward primer sequence 5 Λ -GGCAAAGACAAGCCATAAGC-3 Λ (SEQ ID NO: 8) reverse primer sequence S -ATCCATCAGCAATGACACGA^ (SEQ ID NO:9),

4) marker primers, InD28432 marker primers:

forward primer sequence S -TGCAGACACCACATGCATAA^ (SEQ ID NO: 10) reverse primer sequence S -ACGCATACACACAGGGACAA^ (SEQ ID NO: 11),

5) marker primers, InD2 marker primers:

forward primer sequence S -AACAGACACGTTGCGTCTTG^ (SEQ ID NO: 12) reverse primer sequence S -CTTGCCGCTTAGAGGAGATG^ (SEQ ID NO: 13),

6) marker primers, InD 14 marker primers :

forward primer sequence S -CCACTCTGAAAATCCCAAGC^ (SEQ ID NO: 14) reverse primer sequence S -ACCAGTTAAGTCACGCTCAAA^ (SEQ ID NO: 15),

7) marker primers, RM28466 marker primers:

forward primer sequence 5 Λ -CCG ACGAAGAAGACGAGG AGTAGCC-3 Λ (SEQ ID NO: 16)

reverse primer sequence S -AGGCCGGAGAGCAATCATGTCG^ (SEQ ID NO: 17),

8) marker primers, RM28481 marker primers:

forward primer sequence S -GTCAATTAACCATTGCCCATGC^ (SEQ ID NO: 18) reverse primer sequence S -TTCACGTGGGAACTACTCATGC^ (SEQ ID NO: 19),

9) marker primers, RM28486 marker primers:

forward primer sequence 5,-TTCTCTGAATGCCCTGTCTCTCC-3, (SEQ ID NO:20) reverse primer sequence S -GGCAAATCAGAACAAGTCTCACC^ (SEQ ID NO:21),

10) marker primers, IR2 marker primers: forward primer sequence 5 Λ - AGGATGGGGAGAAGAAGACG-3 Λ (SEQ ID NO:22) reverse primer sequence S -GTGTTCCTTGTCGGGTGTA^ (SEQ ID NO:23), if an amplified fragment of 213 bp can be amplified using the primers RM28438, or an amplified fragment of 221 bp can be amplified using the primers InD28450, or an amplified fragment of 323 bp can be amplified using the primers InD28453, or an amplified fragment of 320 bp can be amplified using the primers InD28432, or an amplified fragment of 241 bp can be amplified using the primers InD2, or an amplified fragment of 397 bp can be amplified using the primers InD14, or an amplified fragment of 85 bp can be amplified using the primers RM28466, or an amplified fragment of 237 bp can be amplified using the primers RM28481, or an amplified fragment of 161 bp can be amplified using the primers RM28486, or an amplified fragment of 228 bp can be amplified using the primers IR2, this indicates the existence of a brown planthopper resistance gene locus Bph9 in rice varieties.

15. A method of screening brown planthopper-resistant rice, amplifying a rice genomic DNA to be detected by PCR using one of the primer pairs of claim 11 , and if an amplified fragment of 213 bp can be amplified using the primers RM28438, or an amplified fragment of 221 bp can be amplified using the primers InD28450, or an amplified fragment of 323 bp can be amplified using the primers InD28453, or an amplified fragment of 320 bp can be amplified using the primers InD28432, or an amplified fragment of 241 bp can be amplified using the primers InD2, or an amplified fragment of 397 bp can be amplified using the primers InD14, or an amplified fragment of 85 bp can be amplified using the primers RM28466, or an amplified fragment of 237 bp can be amplified using the primers RM28481, or an amplified fragment of 161 bp can be amplified using the primers RM28486, or if an amplified fragment of 228 bp can be amplified using the primers IR2 when amplifying a rice genomic DNA to be detected by PCR using the primers IR2 of claim 12, this indicates the existence of brown planthopper resistance in rice varieties.

Description:
RICE BROWN PLANTHOPPER RESISTANCE GENE BPH9 AND MOLECULAR MARKERS, AND USES THEREOF

Field of invention

The present invention belongs to the field of plant genetic engineering, and particularly relates to a rice brown planthopper resistance gene, Bph9, and also to molecular markers of the gene and use of the gene and molecular markers thereof in producing brown

planthopper-resistant rice and rice seeds.

Background art

Rice is an important crop that is a staple food for more than half of the human population in the world. The fine genetic map and physical map of the rice genome have been completed. In addition, rice genome is collinear to genomes of other gramineous crops, making rice a good model monocot plant. The full-scale development of research on functional genomes has become the frontier field of life sciences. Thus, the research on functional genes of rice is of great importance to socio-economic development and biological studies.

The issue of adequate food production is a challenge faced by people all around the world. The yield of rice was greatly increased by two technological revolutions, dwarf breeding in the 1950s and 1960s and hybrid rice cultivation in the 1970s. Brown planthopper is an epidemic and serious pest of rice. Adults and nymphae of brown planthopper pierce and suck rice sap to cause yellow leaf or death, and brown planthopper may spread or induce various rice diseases, leading to yield reduction or loss. Before the 1960s, brown planthopper appeared occasionally only in local rice planting areas in China. Thereafter, with the changes in climate, environment, planting structure, tillage system and cultivation mode, the range of brown planthopper damage spread from the south to the north, the frequency of occurrence increased and the degree of damage worsened. According to the records of China Agriculture Yearbook, there were pandemic outbreaks nationwide in 1966, 1969, 1973, 1977, 1983 and 2003, and there were pandemic mass outbreaks nationwide in 1987, 1991, 2005, 2006 and 2007; the area suffering from brown planthopper damage reached more than 50% of the total area of rice, resulting in serious loss of rice production in China. At present, the area afflicted by rice brown

planthoppers in China is more than 20 million hectares per year, and the direct yield loss caused by brown planthopper damage is more than 2.8 million tons per year. Brown planthopper has become a serious threat to rice production security in China.

At present, brown planthopper has become the number one pest in rice production in China, and poses a serious threat to food security in China. For a long time, the control of brown planthopper has mainly depended on chemical pesticides. As an outbreak of brown planthopper usually occurs at the grain filling stage of rice and the rice plants grow vigorously at this stage, the operation of applying pesticides to the roots of rice plants is very difficult. In fact, the application of large amounts of chemical pesticides year after year has caused pesticide resistance in brown planthopper to increase many times over, resulting in the limited effects of pesticide control. In addition, the applications of chemical pesticides for brown planthopper control, on the one hand, increase the production cost for farmers, and on the other hand, chemical pesticides also cause environmental and ecological problems, such as poisoning of non-target organisms, environmental pollution and food contamination.

The underlying reason for the serious outbreaks of brown planthopper in successive years is that the main rice varieties which are planted in a large area through China have poor resistance to brown planthopper; also, the hybrid rice varieties are of tall plant type and the plants grow in large populations with dense leaves and stems at the middle-late stage in the farm fields and provide a high degree of field closeness and appropriate nutrients, which promote rapid propagation of brown planthopper, and these rice varieties show

hyper-susceptibility to brown planthopper and other pest insects, thus, the epidemic outbreaks easily occur in the case of large insect source size and suitable climatic conditions, causing serious damage (Han Chuan, Liu Guangjie et al, 2003). Actual rice production in the

International Rice Research Institute and Southeast Asia has proven that although the cultivated rice varieties have only moderate-level resistance genes, these are sufficient to keep the populations of brown planthopper below the level of causing damage, so as to prevent serious damage to rice and yield loss. Therefore, the most cost-effective, safe and ecological measure for brown planthopper control is to plant rice varieties containing brown planthopper resistance genes.

The research into brown planthopper resistance genes in rice began in the early 1970s. So far, more than twenty major rice brown planthopper resistance genes have been identified and mapped from common rice cultivars and wild rice resources (for details, see the review paper: Jena et al., 2010. Current status of Brown Planthopper (BPH) resistance and genetics. Rice 2010(3), 161-171). For example, Bphl (Athwal et al.,1971; Hirabayashi and Ogawa, 1995; Sharma et al, 2003; Cha et al, 2008), bph2 (Athwal et al, 1971; Murata et al, 1998; Murai et al., 2001), Bph3 (Lakshminarayana and Khush, 1977; Jairin et al., 2007), bph4 (Kawaguchi et al, 2001), bph5 (Khush et al.,1991), Bph6 (Kabir and Khush, 1988; Qiu et al, 2010), bph7 (Kabir and Khush, 1988), bph8 (Nemoto et al, 1989), Bph9 ((Nemoto et al, 1989; Muruta and Fujiwara, 2001), BphlO (Ishii et al, 1994), Bphll (Takita, 1996), bphl2 (Hirabayashi et al, 1998, 1999), Bphl3(t) (Liu et al, 2001), Bphl4 (Wang et al, 2001; Du et al, 2009), Bphl5 (Huang et al, 2001; Yang et al 2004), Bphl 7 (Renganayaki et al, 2002), Bphl8(t) (Jena et al, 2006), bphl9(t) (Chen et al, 2006), bph20(t), bph21(t), bph22(t), bph23(t), Bph24(t) (Li et al, 2006; Li Rongbai et al, 2008), Bph20, Bph21 (Rahman et al 2009), Bph22(t), Bph23(t) (Ram et al 2010), bph24(t) (Deen et al 2010), bph22(t), bph23(t) (Hou et al 2011), Bph25(t), Bph26(t) (Myint et al. 2005; Yara et al. 2010; Myint et al. 2012). Among these, Bphl4 gene has been successfully cloned, and it is the first rice resistance gene isolated by the map-based cloning technology (Du et al 2009).

Map-based cloning, also known as positional cloning, is a kind of gene cloning

technology that has developed with the development of molecular marker genetic linkage map technology. The map-based cloning method includes subjecting target genes to genetic mapping, physical mapping, sequence analysis and genetic transformation for functional verification. Theoretically, any gene which can be mapped can be isolated by the map-based cloning method. The map-based cloning method is generally suitable for species having relatively small genomes; for example, rice as a monocot model plant has the features of small genome, small genome physical distance/genetic distance ratio and sufficient markers. Rice as a graminaceous model plant has a genome at the center of concentric circles formed by the genomes of seven graminaceous plants including wheat and sorghum, and is one of the crops which are most suitable for target gene isolation through the map-based cloning method. Multiple genes that have been cloned in rice were all cloned by the map-based cloning method, for example, bacterial blight resistance genes Xa-21 (Song WY et al. 1995, A Receptor

Kinase-Like Protein Encoded by the Rice Disease Resistance Gene, Xa21. Science, 270:

1804-1806), Xa-1 (Yoshimura et al. 1998, Expression of Xa-1, a bacterial blight-resistance gene in rice, is induced by bacterial inoculation. PNAS, 95: 1663-1668) and Xa-26 (Sun et al. 2004, Xa26 a gene conferring resistance to Xanthomonas oryzae pv. oryzae in rice, encodes an LRR receptor kinase-like protein. Plant Journal, 37: 517-527), rice blast-resistance genes Pi-b (Wang et al. 1999, The Pi-b gene for rice blast resistance belongs to the nucleotide binding and leucine-rich repeat class of plant disease resistance genes. Plant Journal, 1999, 19: 55-64) and Pi-ta (Bryan et al. 2000, A single amino acid difference distinguishes resistant and susceptible alleles of the rice blast resistance gene Pi-ta. Plant Cell, 12: 2033-2046), tillering genes cloned by Chinese scientists (Li et al. 2003, Control of tillering in rice. Nature 422: 618-621), salt-resistance genes (Ren et al. 2005, A rice quantitative trait locus for salt tolerance encodes a sodium transporter. Nature Genetics 37(10): 1141-1146) and high-yield genes (Weiya Xue et al. 2008, Natural variation in Ghd7 is an important regulator of heading date and yield potential in rice. Nature Genetics 40, 761-767), and the first pest-resistance gene in rice isolated by the map-based cloning method (Du et al. 2009, Identification and characterization of Bphl4, a gene conferring resistance to brown planthopper in rice. PNAS, 106:22163-22168).

Summary of the invention

An objective of the present invention is to provide a rice brown planthopper resistance gene Bph9 and use thereof.

Another objective of the present invention is to provide molecular markers of the brown planthopper resistance gene Bph9 and use thereof.

The present invention constructs segregation populations of brown planthopper-resistant rice by genetic methods and isolates the rice brown planthopper resistance gene Bph9 by means of map-based cloning. The co-segregation marker detection indicates co-segregation of the gene with brown planthopper resistance, and the phenotype of brown planthopper resistance is shown in susceptible rice by genetic transformation of the Bph9 gene, which verifies the function of the gene.

The present invention provides an isolated polynucleotide having the sequence of a rice brown planthopper resistance gene Bph9, said sequence being a nucleotide sequence shown as SEQ ID NO: 1, or a nucleotide sequence formed by the substitution, deletion or insertion of one or more nucleotides in SEQ ID NO: 1 and encoding an amino acid sequence which is the same or similar and has the same function.

The present invention provides an isolated polynucleotide having a cDNA sequence of a rice brown planthopper resistance gene Bph9, the sequence being a nucleotide sequence shown as SEQ ID NO: 2, or a nucleotide sequence formed by the substitution, deletion or insertion of one or more nucleotides in SEQ ID NO: 2 and encoding an amino acid sequence which is the same or similar and has the same function.

The isolated polynucleotide provided in the present invention has a cDNA sequence shown as SEQ ID NO: 2.

The nucleotide sequence of the Bph9 gene provided in the present invention is shown as SEQ ID NO: 1; the gene has a full length of 15628bp and has two introns and three exons, the CDSs of the gene are segments 2963-4073, 6373-6996 and 12663-14960 respectively, the full length of cDNA of the gene is 4042bp, and the gene encodes 1206 amino acids with a protein sequence shown as SEQ ID NO: 3. The protein belongs to the NBS-LRR family and has the following active centers: a 175-322 segment which is a conserved NB-ARC region, a 392-672 segment which is a conserved NB-ARC region (comprising P-loop NTPase, AAA ATPase domain), and an 822-873 segment which is a Leucine rich repeat (LRR).

It will be apparent to those skilled in the art that, on the premise of not affecting the activity of Bph9 protein (i.e. being away from the protein active center), various substitutions, insertions and/or deletions of one or more amino acids in the amino acid sequence shown as SEQ ID NO: 3 can be made to obtain functionally equivalent amino acid sequences.

In addition, considering the degeneracy of codons, for example, the polynucleotide sequence encoding the protein above can be modified in its coding region under a condition of not changing the amino acid sequence or in its non-coding region under a condition of not affecting the protein expression. Therefore, the present invention also contains a nucleotide sequence which results from substitution, insertion and/or deletion of one or more nucleotides in the polynucleotide sequence encoding the protein above, and encodes

equivalently-functional proteins of the polynucleotide sequence.

The polynucleotide fragments above provided in the present invention are operably ligated to a homologous or heterologous promoter sequence.

The present invention also comprises a sense or antisense sequence based on said polynucleotide, comprises a cloning vector or expression vector containing said polynucleotide sequence or its fragments, host cells containing said vector, transformed plant cells and transgenic plants containing said polynucleotide sequence or its fragments.

Said transgenic plant is a monocotyledonous plant.

Said monocotyledonous plant is rice.

The present invention provides the use of a polynucleotide of the invention in selective breeding of rice.

The present invention provides the use of a polynucleotide of the invention in improving brown planthopper resistance of rice.

The present invention provides the use of a polynucleotide of the invention in producing transgenic brown planthopper-resistant rice.

The present invention provides a method for cultivating a plant having brown planthopper resistance, including:

1) transforming plant cells with a polynucleotide of the invention, said polynucleotide containing the rice brown planthopper resistance Bph9 gene and having a nucleotide sequence shown as SEQ ID NO: 1 or SEQ ID NO: 2;

2) regenerating the transformed cells to form a plant;

3) cultivating the regenerated plant and enabling expression of the polynucleotide above. The present invention also provides a method for generating a plant having brown planthopper resistance, said method includes hybridizing the plant having the brown planthopper resistance gene Bph9 with another plant to generate an offspring plant having brown planthopper resistance. In one embodiment the plant is a moncottyledonous plant. In another embodiment, the monocotyledonous plant is a rice plant.

It will be understood by those skilled in the art that molecular markers designed or generated according to the sequences disclosed by the invention can be applied to selective breeding of brown planthopper-resistant rice.

Also, the present invention provides molecular markers linked to the brown planthopper resistance major gene Bph9, which are

RM28438 marker primers:

forward primer sequence S -GTTCGTGAGCCACAACAAATCC^ (SEQ ID NO:4) reverse primer sequence S -GTTAAATGCTCCACCAAACACACC^ (SEQ ID NO:5) or InD28450 marker primers:

forward primer sequence 5 Λ -GGTTGGAAAAGAAGCGATC A-3 Λ (SEQ ID NO:6) reverse primer sequence S -GCATCRTAAGGTTGCCATCA^ (SEQ ID NO:7) or InD28453 marker primers:

forward primer sequence 5 Λ -GGCAAAGACAAGCCATAAGC-3 Λ (SEQ ID NO: 8) reverse primer sequence S -ATCCATCAGCAATGACACGA^ (SEQ ID NO:9) or InD28432 marker primers:

forward primer sequence S -TGCAGACACCACATGCATAA^ (SEQ ID NO: 10) reverse primer sequence S -ACGCATACACACAGGGACAA^ (SEQ ID NO: 11) or InD2 marker primers:

forward primer sequence S -AACAGACACGTTGCGTCTTG^ (SEQ ID NO: 12) reverse primer sequence S -CTTGCCGCTTAGAGGAGATG^ (SEQ ID NO: 13) or InD14 marker primers:

forward primer sequence S -CCACTCTGAAAATCCCAAGC^ (SEQ ID NO: 14) reverse primer sequence S -ACCAGTTAAGTCACGCTCAAA^ (SEQ ID NO: 15) or RM28466 marker primers:

forward primer sequence 5 Λ -CCG ACGAAGAAGACGAGG AGTAGCC-3 Λ (SEQ ID NO: 16)

reverse primer sequence S -AGGCCGGAGAGCAATCATGTCG^ (SEQ ID NO: 17) or RM28481 marker primers:

forward primer sequence S -GTCAATTAACCATTGCCCATGC^ (SEQ ID NO: 18) reverse primer sequence S -TTCACGTGGGAACTACTCATGC^ (SEQ ID NO: 19) or RM28486 marker primers:

forward primer sequence S -TTCTCTGAATGCCCTGTCTCTCC^ (SEQ ID NO:20) reverse primer sequence S -GGCAAATCAGAACAAGTCTCACC^ (SEQ ID NO:21), the rice genomic DNA is amplified using the above marker primers; and if an amplified fragment of 213 bp can be amplified using the primers RM28438, or an amplified fragment of 221 bp can be amplified using the primers InD28450, or an amplified fragment of 323 bp can be amplified using the primers InD28453, or an amplified fragment of 320 bp can be amplified using the primers InD28432, or an amplified fragment of 241 bp can be amplified using the primer InD2, or an amplified fragment of 397 bp can be amplified using the primers InD14, or an amplified fragment of 85 bp can be amplified using the primers RM28466, or an amplified fragment of 237 bp can be amplified using the primers RM28481, or an amplified fragment of 161 bp can be amplified using the primers RM28486, this indicates the existence of a brown planthopper resistance major gene locus Bph9 in rice varieties. Therefore, the molecular markers RM28438, InD28450, InD28453, InD28432, InD2, InD14, RM28466, RM28481 and RM28486 can be applied to screening of brown planthopper-resistant rice containing the brown planthopper resistance gene Bph9.

The present invention also provides another molecular marker of the rice brown planthopper resistance gene Bph9, which is obtained by PCR using InDel molecular marker IR2 primers, and the primers are:

forward primer sequence 5 Λ - AGGATGGGGAGAAGAAGACG-3 Λ (SEQ ID NO:22) reverse primer sequence S -GTGTTCCTTGTCGGGTGTA^ (SEQ ID NO:23).

The present invention also provides molecular markers related to rice brown planthopper resistance, which are

RM28438 marker primers:

forward primer sequence S -GTTCGTGAGCCACAACAAATCC^ (SEQ ID NO:4) reverse primer sequence S -GTTAAATGCTCCACCAAACACACC^ (SEQ ID NO:5), or InD28450 marker primers:

forward primer sequence 5 Λ -GGTTGGAAAAGAAGCGATC A-3 Λ (SEQ ID NO:6) reverse primer sequence S -GCATCRTAAGGTTGCCATCA^ (SEQ ID NO:7), or InD28453 marker primers:

forward primer sequence 5 Λ -GGCAAAGACAAGCCATAAGC-3 Λ (SEQ ID NO: 8) reverse primer sequence S -ATCCATCAGCAATGACACGA^ (SEQ ID NO:9), or InD28432 marker primers:

forward primer sequence S -TGCAGACACCACATGCATAA^ (SEQ ID NO: 10) reverse primer sequence S -ACGCATACACACAGGGACAA^ (SEQ ID NO: 11), or InD2 marker primers:

forward primer sequence S -AACAGACACGTTGCGTCTTG^ (SEQ ID NO: 12) reverse primer sequence S -CTTGCCGCTTAGAGGAGATG^ (SEQ ID NO: 13), or InD14 marker primers:

forward primer sequence S -CCACTCTGAAAATCCCAAGC^ (SEQ ID NO: 14) reverse primer sequence S -ACCAGTTAAGTCACGCTCAAA^ (SEQ ID NO: 15), or RM28466 marker primers:

forward primer sequence 5 Λ -CCG ACGAAGAAGACGAGG AGTAGCC-3 Λ (SEQ ID NO: 16)

reverse primer sequence S -AGGCCGGAGAGCAATCATGTCG^ (SEQ ID NO: 17), or RM28481 marker primers:

forward primer sequence S -GTCAATTAACCATTGCCCATGC^ (SEQ ID NO: 18) reverse primer sequence S -TTCACGTGGGAACTACTCATGC^ (SEQ ID NO: 19), or RM28486 marker primers:

forward primer sequence S -TTCTCTGAATGCCCTGTCTCTCC^ (SEQ ID NO:20) reverse primer sequence S -GGCAAATCAGAACAAGTCTCACC^ (SEQ ID NO:21),

IR2 primers, and the primers are:

forward primer sequence 5 Λ - AGGATGGGGAGAAGAAGACG-3 Λ (SEQ ID NO:22) reverse primer sequence S -GTGTTCCTTGTCGGGTGTA^ (SEQ ID NO:23).

The present invention also provides the use of the molecular markers in selective breeding of brown planthopper-resistant rice.

The present invention provides a molecular marker method for the rice brown planthopper resistance gene bph9, which amplifies a rice genomic DNA to be detected using one of the following primer pairs and detects the product of amplification:

1) marker primers, RM28438 marker primers:

forward primer sequence S -GTTCGTGAGCCACAACAAATCC^ (SEQ ID NO:4) reverse primer sequence S -GTTAAATGCTCCACCAAACACACC^ (SEQ ID NO:5),

2) marker primers, InD28450 marker primers:

forward primer sequence 5 Λ -GGTTGGAAAAGAAGCGATC A-3 Λ (SEQ ID NO:6) reverse primer sequence S -GCATCRTAAGGTTGCCATCA^ (SEQ ID NO:7),

3) marker primers, InD28453 marker primers:

forward primer sequence 5 Λ -GGCAAAGACAAGCCATAAGC-3 Λ (SEQ ID NO: 8) reverse primer sequence S -ATCCATCAGCAATGACACGA^ (SEQ ID NO:9),

4) marker primers, InD28432 marker primers: forward primer sequence S -TGCAGACACCACATGCATAA^ (SEQ ID NO: 10) reverse primer sequence S -ACGCATACACACAGGGACAA^ (SEQ ID NO: 11),

5) marker primers, InD2 marker primers:

forward primer sequence S -AACAGACACGTTGCGTCTTG^ (SEQ ID NO: 12) reverse primer sequence S -CTTGCCGCTTAGAGGAGATG^ (SEQ ID NO: 13),

6) marker primers, InD 14 marker primers :

forward primer sequence S -CCACTCTGAAAATCCCAAGC^ (SEQ ID NO: 14) reverse primer sequence S -ACCAGTTAAGTCACGCTCAAA^ (SEQ ID NO: 15),

7) marker primers, RM28466 marker primers:

forward primer sequence 5 Λ -CCGACGAAGAAGACGAGG AGTAGCC-3 Λ (SEQ ID NO: 16)

reverse primer sequence S -AGGCCGGAGAGCAATCATGTCG^ (SEQ ID NO: 17),

8) marker primers, RM28481 marker primers:

forward primer sequence S -GTCAATTAACCATTGCCCATGC^ (SEQ ID NO: 18) reverse primer sequence S -TTCACGTGGGAACTACTCATGC^ (SEQ ID NO: 19),

9) marker primers, RM28486 marker primers:

forward primer sequence 5 , -TTCTCTGAATGCCCTGTCTCTCC-3 , (SEQ ID NO:20) reverse primer sequence S -GGCAAATCAGAACAAGTCTCACC^ (SEQ ID NO:21),

10) marker primers, IR2 marker primers:

forward primer sequence 5 Λ - AGGATGGGGAGAAGAAGACG-3 Λ (SEQ ID NO:22) reverse primer sequence S -GTGTTCCTTGTCGGGTGTA^ (SEQ ID NO:23).

if an amplified fragment of 213 bp can be amplified using the primers RM28438, or an amplified fragment of 221 bp can be amplified using the primers InD28450, or an amplified fragment of 323 bp can be amplified using the primers InD28453, or an amplified fragment of 320 bp can be amplified using the primers InD28432, or an amplified fragment of 241 bp can be amplified using the primers InD2, or an amplified fragment of 397 bp can be amplified using the primers InD 14, or an amplified fragment of 85 bp can be amplified using the primers RM28466, or an amplified fragment of 237 bp can be amplified using the primers RM28481, or an amplified fragment of 161 bp can be amplified using the primers RM28486, or an amplified fragment of 228 bp can be amplified using the primers IR2, this indicates the existence of a brown planthopper resistance gene locus Bph9 in rice varieties.

The present invention also provides a method of screening brown planthopper-resistant rice, which amplifies a rice genomic DNA to be detected by PCR using one of the above primer pairs; and if an amplified fragment of 213 bp can be amplified using the primers RM28438, or an amplified fragment of 221 bp can be amplified using the primers InD28450, or an amplified fragment of 323 bp can be amplified using the primers InD28453, or an amplified fragment of 320 bp can be amplified using the primers InD28432, or an amplified fragment of 241 bp can be amplified using the primers InD2, or an amplified fragment of 397 bp can be amplified using the primers InD14, or an amplified fragment of 85 bp can be amplified using the primers RM28466, or an amplified fragment of 237 bp can be amplified using the primers RM28481, or an amplified fragment of 161 bp can be amplified using the primers RM28486, or an amplified fragment of 228 bp can be amplified using the primers IR2, this indicates the existence of brown planthopper resistance in rice varieties.

The Bph9 gene provided in the present invention is obtained by cloning by the following steps:

1. Creation of a mapping population. An F 2 population is obtained by hybridization of a brown planthopper-resistant rice variety and a common rice variety and inbreeding of the Fi generation, and is used as a mapping population for the brown planthopper resistance gene.

2. Identification of brown planthopper resistance. The brown planthopper resistance of the mapping population is identified by the standard seedbox screening technique. Seeds are harvested from the F 2 -generation plants and the seeds harvested from each F 2 -generation plant are sowed in a seedling tray to generate 20 seedlings (called one line). At the two-euphylla one-apical bud stage, the lines are exposed to 2-4 years old brown planthopper nymphae (10 nymphae/plant), the damage condition of each line is recorded, and each material is tested with three replications. According to the results of resistance identification, the resistance scores of plant lines in the mapping populatoin are evaluated.

3. Mapping of the brown planthopper resistance gene. The segregation of SSR and RFLP molecular markers in each individual F 2 plant is detected by PCR (polymerase chain reaction) and polyacrylamide gel electrophoresis, as well as RFLP markers and Southern hybridization; and in combination with the resistance score of each corresponding line, a molecular marker genetic linkage map of rice chromosome 12 is constructed by the software JoinMap3.0 and MapQTL5.0 to map the gene Bph9 between the molecular markers RM28438 and RM28486.

4. Molecular marking and fine mapping of encrypted target segments. Primers of the SSR markers and InDel markers of the target segment where the Bph9 of chromosome 12 is located are designed according to the rice genome sequences published by the International Rice Genome Sequencing Project, the segregation of the markers in the BC 2 F2 large population is detected by PCR and polyacrylamide gel electrophoresis, and based on the relationship between phenotype and genotype of recombinant individual plants which are obtained by screening, the brown planthopper resistance gene Bph9 is mapped between the molecular markers InD2 and InD18 and is closely linked to the marker InD14.

5. Determination of candidate genes. A Fosmid genome library of a resistant parent rice material (Pokkali, IRGC 108921) containing the brown planthopper resistance gene Bph9 is constructed, the PCR screening is performed through mapping interval molecular markers to obtain a positive clone covering the Bph9 mapping interval, the large fragment sequencing is performed by the dideoxy chain-termination method (Sanger method) to obtain a genome sequence of the segment where Bph9 is located, and candidate genes of Bph9 are determined by gene prediction using the software RiceGAAS and comparative analysis of the sequences of the Japonica rice variety 'Nipponbare'and the variety 9311.

6. Co-segregation detection using primers designed according to the sequences.

Primers are designed according to the Bph9 candidate gene sequences, the BC 3 F2 large population is tested by PCR and polyacrylamide gel electrophoresis, the markers

corresponding to these primers show co-segregation with the phenotype of brown planthopper resistance, and brown planthopper-resistant rice lines are screened out.

7. Full-length cDNA cloning. According to the predicted cDNA sequence, primers are designed using the 3 '-end sequence and a 1692bp fragment is amplified from the cDNA of brown planthopper-resistant rice, primers are designed using the fragment sequence, the 3 '-end and 5 '-end sequences of the cDNA are obtained by RACE (RAPID AMPLIFICATION of cDNA Ends), and finally the full-length cDNA of Bph9 is obtained.

However, it will be understood by those skilled in the art that the Bph9 gene can be amplified from the brown planthopper-resistant rice genome by designing appropriate PCR primers according to the nucleotide sequences of Bph9 disclosed by the invention.

8. Genetic transformation of the Bph9 gene for its functional verification. According to the screening and sequencing results of the Fosmid genome library, a 3026 bp fragment which is obtained by double digesion of the Fosmid clone where the Bph9 gene is located with Sail and Ncol is used as a Bph9 gene promoter region (there is a translation initiation codon of the Bph9 gene at the Ncol site).

The full-length cDNA of the gene Bph9 is subjected to double digesion with Ncol and Xhol to obtain a 3346 bp fragment which comprises most of the ORF region of the Bph9 gene and also comprises a large part of the No. 3 exon (the Xhol site is located at the terminal of the No. 3 exon). The Bph9 genome has a sequence length of 15628 bp and has two introns and three exons.The ORF length of the gene is 3621 bp, there is an Xhol site at 3344 bp, and the Xhol site is located at the terminal of the No. 3 exon. The Fosmid clone where the Bph9 gene is located is subjected to double digestion with Xhol and EcoRI to obtain a 1291 bp fragment, and the fragment comprises the part behind the Xhol site of the No. 3 exon and the transcriptional termination region of the Bph9 gene. The above fragments are ligated to the Ncol and EcoRI sites of a pGEM T easy vector by means of three-fragment ligation. A 4637 bp fragment which is obtained by double digestion with Ncol and EcoRI comprises the complete ORE of the Bph9 gene and the transcriptional termination region of the gene.

The Bph9 gene promoter region (3026 bp fragment) which is obtained by double digestion with Sail and Ncol and the complete ORE and transcriptional termination region of the Bph9 gene (4637 bp fragment) which is obtained by double digestion with Ncol and EcoRI are ligated to the Sail and EcoRI sites of pCAMBIA1301 by means of three-fragment ligation. After verification by sequencing, it is proven that the resulting vector is the Bph9 gene genetic transformation vector (using its promoter region, complete ORF and its transcriptional termination region), and the vector is transformed into Agrobacterium tumefaciens EHA105 through electroporation.

By the Agrobacterium tumefaciens EHA 105 -mediated genetic transformation method, the Bph9 gene vector (using its promoter region, complete ORF and its transcriptional termination region) is introduced into a normal Indica rice variety Kasalath, and finally 15 5/?/i9-positive plants are obtained. The resistance is identified by the standard seedbox screening technique using the Ti-generation Bph9 transgenic plants, and the result shows that all the plants of the control rice variety Kasalath die and the transgenic positive plants survive with a resistance score of 2-3, indicating that the Bph9 gene has a function of resistance to brown planthopper. Therefore, the brown planthopper resistance gene Bph9 can be applied in rice and can also be applied in rice seeds to cultivate rice varieties having brown planthopper resistance.

The present invention has the following advantages and benefits:

1. The successful cloning of the gene further verifies the reliability of cloning important genes of rice by the map-based cloning method, and the gene cloned by the method has definite functions and good effects.

2. Although multiple genes that encode proteins having the NBS structure in rice have been cloned, most of them are related to disease resistance, while the Bph9 gene cloned in the invention has obvious resistance to brown planthopper, which is of importance to the comprehensive understanding of the biological functions of such genes.

3. Except for the Bphl4 gene which was cloned in 2009, no other rice brown planthopper resistance genes have been successfully cloned anywhere in the world as yet, and the molecular mechanism of brown planthopper resistance in rice is still unknown. However, the Bph9 gene cloned in the invention can significantly improve the rice resistance to brown planthopper, which will play an important role in promoting research on the molecular mechanism of brown planthopper resistance in rice. 4. The brown planthopper resistance in rice can be greatly improved through the gene Bph9; the gene Bph9 is applied to breeding of rice by genetic transformation or

hybridization, which can improve brown planthopper resistance in rice varieties to reduce the pest damage of brown planthopper and achieve the purposes of increased yield and stable yield.

5. Piercing-sucking insects are a broad category of pest insects in agricultural production, the success in Bph9 gene cloning and brown planthopper resistance verification provides an important reference for research on piercing-sucking insect resistance in other plants.

Brief description of the sequences in the sequence listing

SEQ ID NO: 1 is a Bph9 rice genomic sequence.

SEQ ID NO: 2 is a Bph9 cDNA.

SEQ ID NO: 3 is a Bph9 amino acid sequence.

SEQ ID NO: 4-27 are primer sequences useful in the invention.

Description of drawings

Fig. 1 is an image showing the results of identifying resistant plants and susceptible plants in F 2 :3 lines by the standard seedbox screening technique. As shown in the figure, P09-1 to P09-16 refer to the corresponding F 2:3 lines obtained by inbreeding of each F 2 individual plant in the Bph9-containing F 2 population which is constructed by hybridization of a brown planthopper-resistant parent Pokkali (IRGC 108921, containing the brown planthopper resistance gene Bph9) and a brown planthopper-susceptible rice variety Yangdao No. 6 (93-11). As shown in the figure, 7 days after the brown planthopper pest occurred, the control susceptible variety Taichung local No. 1 (TNI) are obviously dead, but the P09-1, P09-2, P09-8, P09-11, P09-12 and P09-13 F 2:3 lines survive after the brown planthopper pest occurs, the plants growing healthily, so they are resistant plants; and as shown in the figure, the P09-7, P09-9, P09-10 F 2:3 lines die after the brown planthopper pest occurs and so are susceptible plants.

Fig. 2 is an electropherogram of detecting individual plants using SSR marker RM28486. The first two track lanes are of the resistant parent Pokkali (IRGC 108921) and the susceptible parent Yangdao No. 6 (93-11) respectively, and the following track lanes are of the F 23 lines constructed by hybridization of Pokkali and Yangdao No. 6. As shown in the figure, the No. 2, 3, 5, 6, 8, 10, 12, 14, 15, 18, 19, 20, 21 and 23 F 23 lines, from which a 161 bp fragment can be specifically amplified using the SSR marker RM28486 linked to the brown planthopper resistance gene Bph9, all show resistance to brown planthopper, while the No. 1, 4, 7, 9, 11, 13, 16, 17, 22 and 24 F 23 lines, from which the 161bp specific fragment cannot be amplified, all show susceptibility to brown planthopper.

Fig. 3 is a mapping of Bph9 in a rice chromosome. A: the result of Bph9 primary mapping. The marker names are shown above the chromosome, the numbers refer to the genetic distance (cM) between the markers, the result of QTL scanning shows that there is a maximum LOD value of 44.1 between the molecular markers RM28486 and RM28438, and the distance between RM28486 and RM28438 is 1.7cM. n represents the number of individual plants in the F 2 mapping population.

B: the screening result for individual plants with recombination between the molecular markers RM28486 and RM28438. With the integration of molecular marker analysis and brown planthopper resistance phenotype results, Bph9 is finely mapped between the molecular markers InD2 and RM28466, and shows co-segregation with the marker InD14. The numbers below the molecular markers represent the quantity of recombinant individual plants between the two molecular markers, n represents the quantity of individual plants of BC 2 F 2 population for recombinant individual plant screening.

C: the physical map between InD2 and RM28466; Bph9 is located within a region of about 68 kb between InD2 and RM28466. 19 and 544-22 are Fosmid clones which are mutually overlapped and cover the interval of the markers InD2 and RM28466.

Fig. 4 is an image showing the results of identifying brown planthopper resistance in transgenic plants containing a transformation vector comprising the promoter region, complete ORF and transcriptional termination region of the Bph9 gene. 1 and 9 represent the susceptible control variety TNI, 2 represents the resistant parent Pokkali (IRGC 108921), 3, 5 and 7 represent the susceptible control variety Kasalath, 4, 6 and 8 represent the transgenic plant lines POK1, POK2 and POK3 containing a transformation vector comprising the promoter region, complete ORF and transcriptional termination region of the Bph9 gene. Compared by the standard seedbox screening technique before insect exposure (the figure above) and 7 days after insect exposure (the figure below), the control susceptible varieties Kasalath and TNI are obviously dead, while the resistant parent Pokkali (IRGC 108921) and transgenic plant lines POK1, POK2 and POK3 still survive and the plants grow healthily.

Fig. 5 is an image showing the results of identifying brown planthopper resistance in transgenic plants containing a genome complementary vector of the Bph9 gene. The TO-generation transgenic plants and the susceptible control variety TNI are transplanted diagonally, the four plants forming a square-like shape after transplantation, in which 1 and 4 represent the susceptible control variety TNI, 2 represents the Bph9 gene genome

complementary vector-positive TO-generation transgenic plant PGKl, and 3 represents the Bph9 gene genome complementary vector-positive transgenic plant TO-generation PGK2. At the tillering stage, 100 2-3-year old brown planthopper nymphae are applied; and 28 days after exposure to brown planthopper, the whole plants of susceptible control variety TNI are dead, while the Bph9 gene genome complementary vector-positive transgenic plants PGKl and PGK2 still survive and grow healthily without leaf damage.

Fig. 6 is an example of a functional molecular marker IR2 (belonging to the InDel markers) developed according to the Bph9 genome sequence, and the length of an amplified fragment is 228 bp. In the figure, 1 represents the resistant parent Pokkali (IRGC 108921) carrying the brown planthopper resistance gene Bph9, 2 represents the susceptible material Yangdao No. 6 (93-11), 3 represents a material which is screened out from the backcross offspring of Pokkali and Yangdao No. 6 using the functional molecular marker IR2 and carries the brown planthopper resistance gene Bph9 (the material is resistant to brown planthopper).

Fig. 7 refers to brown planthopper-resistant rice having the Bph9 gene, which is obtained by means of molecular marker-assisted selective breeding. The brown planthopper resistance is identified at the seedling stage and the insect source is brown planthopper populations in the farm fields in Wuhan city. In the figure, 1, 5 and 9 represent the susceptible control variety TNI, 2 and 6 represent the resistant parent Pokkali (IRGC 108921), 3 and 7 represent the susceptible material Yangdao No. 6 (93-11), and 4 and 8 represent a cultivar Luoyang No. 9 (having the genetic background of Yangdao No. 6 and carrying the brown planthopper resistance gene Bph9). Compared by the standard seedbox screening technique before insect exposure and 7 days after insect exposure, in which the figure above is an image taken before insect exposure and the figure below is an image taken 7 days after insect exposure, the control susceptible variety TNI and the recipient parent Yangdao No. 6 are obviously dead, while the resistant parent Pokkali (IRGC 108921) and the cultivar Luoyang No. 9 (having the genetic background of Yangdao No. 6 and carrying the brown planthopper resistance gene Bph9) still survive and the plants grow healthily.

Fig. 8 refers to brown planthopper-resistant rice having the Bph9 gene, which is obtained by means of molecular marker-assisted selective breeding. The brown planthopper resistance is identified at the seedling stage and the insect sources are brown planthopper biotype I, biotype II and biotype III. The figure above refers to the insect source brown planthopper biotype I, the middle figure refers to the insect source brown planthopper biotype II and the figure below refers to the insect source brown planthopper biotype III. In the figure, 1 and 6 represent the susceptible control variety TNI, 2 and 4 represent the cultivar Luoyang No. 9 (having the genetic background of Yangdao No. 6 and carrying the brown planthopper resistance gene Bph9), and 3 and 5 represent the susceptible material Yangdao No. 6 (93-11). After exposure to the insects, the susceptible recipient parent Yangdao No. 6 and the variety Taichung local No. 1 are obviously dead, while the cultivar Luoyang No. 9 (having the genetic background of Yangdao No. 6 and carrying the brown planthopper resistance gene Bph9) still survives and the plants grow healthily.

Fig. 9 refers to brown planthopper-resistant rice having the Bph9 gene, which is obtained by means of molecular marker-assisted selective breeding. The brown planthopper resistance is identified at the near-tillering stage and the insect sources are brown planthopper populations in the farm fields in Wuhan city. After exposure to insects, the susceptible recipient parent Yangdao No. 6 and the variety Taichung local No. 1 are obviously dead, while the cultivar Luoyang No. 9 (having the genetic background of Yangdao No. 6 and carrying the brown planthopper resistance gene Bph9) still survives and the plants grow healthily.

Fig. 10 refers to brown planthopper-resistant rice having the Bph9 gene, which is obtained by means of molecular marker-assisted selective breeding. The brown planthopper resistance is identified at the maturity stage and the insect sources are brown planthopper populations in farm fields in Wuhan city, and after exposure to insects, the susceptible recipient parent Yangdao No. 6 is obviously dead and the stems are withered. However, the cultivar Luoyang No. 9 (having the genetic background of Yangdao No. 6 and carrying the brown planthopper resistance gene Bph9) still survives, the stems are upright and the plants grow healthily.

Brief description of the preferred embodiments

The following embodiments are intended to further illustrate the contents of the present invention and not to be construed as limitations to the invention. Various modifications or replacements to the method, procedures or conditions of the invention made without departing from the spirit and substance of the invention are within the scope of the invention.

If not particularly specified, all the technical means used in the embodiments are well known by the skilled persons in the art.

Example 1. Positional cloning and development of linked molecular markers of the Bph9 gene 1. Results of Bph9 primary mapping

A brown planthopper-resistant parent Pokkali (IRGC 108921, containing the brown planthopper resistance gene Bph9) and a brown planthopper-susceptible rice variety Yangdao No. 6 (93-11) are hybridized to construct a Bph9-containing F 2 population; the varities 93-11 and Pokkali (IRGC 108921) are both from the National Crop Germplasm Preservation Center of the Institute of Crop Science, Chinese Academy of Agricultural Sciences, and the

genomic DNAs of individual plants of the parents and F 2 population are extracted by the CTAB method (Murray MG & Thompson, 1980 Rapid isolation of high-molecular- weight plant DNA. Nucleic Acids Res 8: 4321-4325). Each F 2 individual plant is inbred to harvest a corresponding F 2:3 line. In order to identify the brown planthopper resistance phenotype of each individual plant in the F 2 mapping population, the resistance performance of each individual plant in the F2:3 lines is observed by the standard seedbox screening technique (see Fig. l), and the brown planthopper resistance phenotypes of F 2 individual plants are represented by the resistance scores of the F 2:3 lines. In order to ensure consistent growth of each line in the parents and F 2:3 population, all the tested materials are subjected separately to seed soaking for germination promotion before sowing. 60 seeds of each line (variety) are sowed in a bread box which is 58 cm long, 38 cm wide and 9 cm high and filled with nutrient soil to 7 cm thickness. Each material is re-sowed with three replications in each box, with three replications of random sowing for the parents and TNI (susceptible control) respectively. The seedlings are thinned 7 days after sowing to remove diseased and weak seedlings. When the seedlings have grown to the two-euphylla one-apical bud stage, 2-3 -year old nymphae of brown planthopper are inoculated at a ratio of 8 nymphae/seedling, and finally a nylon gauze mesh is used to cover. When all the plants of the susceptible variety TNI (Taichung local No. 1) are dead, the resistance (Table 1) of each individual plant is evaluated (with a score of 0, 1, 3, 5, 7 or 9) with reference to the method proposed by Huang et al, (Huang Z et al, 2001 Identification and mapping of two brown planthopper resistance genes in rice. Theor. Appl. Genet. 102, 929-934); and for each line of the parent materials and populations, the resistance score of the line is evaluated by means of weighted average calculation, and the genotype of this individual plant is predicted according to the resistance score.

Table 1. Scoring standards for identifying resistance and susceptibility to brown planthopper.

Resistance Damage degree (observed when more than 90% of Taichung Resistance score local No. 1 are dead) level

0 Healthy growth of plants, no leaf damage Resistant (R)

1 One yellow leaf Resistant (R) 3 One to two yellow leaves, or one withered leaf Medium resistant (MR)

5 Two to three yellow leaves, or two withered leaves Medium resistant (MR)

7 Three to four withered leaves, but no death of plants Susceptible (S)

9 Death of the whole plants Susceptibe (S)

The result of identification by the standard seedbox screening technique shows that the resistance scores of the varieties Pokkali (IRGC 108921) and 9311 are 1.9 and 8.8 respectively, indicating that the variety Pokkali (IRGC 108921) is resistant to brown planthopper but the variety 9311 is susceptible to brown planthopper. The frequency distribution of brown planthopper resistance scores of the 135 F 2: 3 lines is a continuous distribution, with the minimum value of 2.1 and maximum value of 9.0. According to the brown planthopper resistance scores, the F 2: 3 lines are classified as the following three phenotypes: resistance, resistance/susceptibility segregation and susceptibility; while the genotypes of the

corresponding F 2 individual plants are recorded as the following three types: RR (homozygous resistance), Rr (heterozygous resistance) and rr (homozygous susceptibility), respectively. The segregation of resistance/susceptibility to brown planthopper in the F 2 population

complies with the ratio of 1 :2: 1 (χ 2 = 1.31, χ 2 ο.ο5, ι = 3.84) (Table 2).

Table 2. Segregation ratio of resistance/susceptibility to brown planthopper in 135 individual plants of 9311 /Pokkali F 2 segregating population

F 2 genotype a Number of F 2 Phenotype of the

individuals' 5 corresponding F 2: 3 line 0

~ RR 36 RS < 4

Rr 61 4<RS< 7

rr 38 7 < RS

a RR, homozygous resistance; Rr, heterozygous resistance; rr, homozygous susceptibility; b lRR:2Rr: lrrr adaptability test value: χ 2 = 1.31, χ 2 ο.ο5,ι = 3.84; c resistance score value: RS, Resistance Score

According to the markers published on the Gramene website (www.gramene.org/), a certain number of SSR molecular markers are selected with a relatively uniform genetic distance on each chromosome. In addition, based on the last mapping segment of the gene, the corresponding genome sequences of the rice variety 9311 and Japonica rice variety

'Nipponbare' are compared, SSR motifs are searched for using the SSR search tool SSRIT (http://www.gramene.org/db/markers/ssrtool), and primers are designed according to their flanking sequences and serve as alternative markers. The setting parameters of the SSRIT are that: the maximum motif length is a tetramer, the minimum repeat is 5, and all the SSR motifs are searched. All the SSR motifs having more than 15 bases (motif length x repeat) are selected. Also, according to the corresponding genome sequences of the rice variety 9311 and Japonica rice variety 'Nipponbare' in the public database, the inserted/deleted sites existing in the genome sequences are searched for by the software PowerBlast, and the InDel markers are developed by the software Primer Premier 5.0.

The analysis of the SSR markers is done with reference to the method proposed by Temnykh (Temnykh S et al, 2000. Mapping and genome organization of microsatellite sequences in rice. Theor Appl Genet 100: 697-712). The 10 μΐ reaction system comprises: 10 mM Tris-HCl pH 8.3, 50 mM KC1, 1.5 mM MgCl 2 , 50 μΜ dNTPs, 0.2 μΜ primers, 0.5U Taq polymerase and 20 ng DNA template. The amplification reaction takes place on a PTC- 100 PCR instrument: 94°C 2 min, 94°C 15 sec, 55°C 30 sec, 72°C 1.5 min, 35 cycles, 72°C 5 min. The product of amplification is separated using 6% Native-PAGE and developed by silver staining (Zhu et al, 2004. Identification and characterization of a new blast resistance gene located on rice chromosome 1 through linkage and differential analyses. Phytipathology 94:515-519). The amplified DNA bands are observed using a lamp box equipped with a fluorescent lamp. The result is recorded, and the primers having a polymorphism between parents are analyzed in the F 2 population to obtain the population genotype data.

According to the resistance scores of the F 2 : 3 lines, DNAs of 10 extremely resistant individual plants and DNAs of 10 extremely susceptible individual plants are selected and hybridized to construct resistance/susceptibility pools. Also, the resistance/susceptibility pools are separately screened using the primers having a polymorphism between parents and molecular markers having a polymorphism between resistance/susceptibility pools are obtained, and it is indicated that such polymorphic markers are linked to resistance. Then, according to the chromosome where the linked markers are located, the primers having a polymorphism between parents on the chromosome are selected to screen individual plants of the F 2 segregating population, the PCR process being the same as above, and the population genotype data is obtained. According to the law of linkage and crossing-over, the population genotype data is processed by the software JoinMap 3.0 to construct a partial genetic map of rice and to obtain the genetic distance between molecular markers. Finally, in combination with the molecular marker genotype data of individual plants in the F 2 population and the corresponding resistance scores from brown planthopper resistance identification, the QTL scan of the target chromosome is performed by composite interval mapping using the software MapQTL 5.0. The result shows that a QTL exists between RM28486 and RM28438 on the long arm of chromosome 12, with an LOD value of 44.1 and a contribution rate of 77.8%, and the distance between the molecular markers RM28486 and RM28438 where the QTL is located is 1.7 cM (see Fig. 3A). The selection accuracy of RM28486 and RM28438 in the F 2 population can reach 98% to 99%.

2. Fine mapping of Bph9

As the physical distance between RM28486 and RM28438 is large, the distance is about 520 kb in the sequenced Japonica rice variety 'Nipponbare', and is about 450 kb in the sequenced Indica rice variety 9311. In order to search for the markers more closely linked to Bph9, according to the mapping results of QTL, the present invention adopts PCR (polymerase chain reaction) and polyacrylamide gel electrophoresis to screen 3000 individual plants of the BC 2 F 2 population using the SSR markers RM28486 and RM28438 on two sides, obtaining 32 individual plants with recombination between the two markers.

According to the corresponding genome sequences of the rice variety 9311 and Japonica rice variety 'Nipponbare' in the SSR markers RM28486 and RM28438 segment in the public database, SSR motifs are searched for using the SSR search tool SSRIT

(http://www.gramene.org/db/markers/ssrtool), and primers are designed according to their flanking sequences and serve as alternative markers. Also, the inserted/deleted sites existing in the genome sequences are searched for by the software PowerBlast, and the InDel markers are developed for by the software Primer Premier 5.0. Molecular marker encryption is performed on 32 individual plants with recombination between the two markers RM28486 and RM28438 using these newly developed SSR markers and InDel markers, so as to construct a saturated linkage map, and in combination with the resistance identification results of the recombinant individual plants, finally the Bph9 gene is mapped between InD2 and RM28466 and closely linked to the markers InD14 (see Table 3, Fig. 3B).

Table 3 Genotypes and phenotypes of a part of recombinant individual plants of BC 2 F 2 and

BC 3 F 2 screened using molecular markers

indiviphe- resistdual RM28 InD InD InD InD InD RM2 RM2 RM2 no- ance plant 438 2845 2845 2843 2 14 b 8466 8481 8486 type score

No. 0 3 2

93-1 l a S s S S S S S S S S 8.8

3A1 S s S S S S S H H S 8.7

3A2 H H H H H H S S S H 4.3 3A3 H H H H H H R R R H 5.3

3A4 R R R R R R H H H R 3.3

3A5 S S S S S H H H H H 5.3

3A6 H H H H H S S S S S 8.7

3A7 R R R R R H H H H H 4.8

3A8 H H H H S S S S S S 8.6

Pokkali

(IRGC

108921) R R R R R R R R R R 1.9 a 93-11 and Pokkali (IRGC 108921) are two parent materials, and the others are parts of recombinant individual plants; b as shown in the table, the molecular markers InD14 are cosegregated with resistance phenotype. R represents the genotype and phenotype of the resistant parent Pokkali (IRGC 108921), S represents the genotype and phenotype of the susceptible parent 9311, and H represents the heterozygous genotype and phenotype.

3 . Molecular markers linked to the brown planthopper resistance gene Bph9

In the sequenced Japonica rice variety 'Nipponbare', the physical distance between InD2 and RM28466 is 129 kb; and in the sequenced Indica rice variety 9311, the physical distance between InD2 and RM28466 is 113kb. Therefore, the use of the molecular markers in the saturated linkage map in Fig. 3B is the use of:

RM28438 marker primers:

forward primer sequence S -GTTCGTGAGCCACAACAAATCC^ (SEQ ID NO:4) reverse primer sequence S -GTTAAATGCTCCACCAAACACACC^ (SEQ ID NO:5), or InD28450 marker primers:

forward primer sequence 5 Λ -GGTTGGAAAAGAAGCGATC A-3 Λ (SEQ ID NO:6) reverse primer sequence S -GCATCRTAAGGTTGCCATCA^ (SEQ ID NO:7), or InD28453 marker primers:

forward primer sequence 5 Λ -GGCAAAGACAAGCCATAAGC-3 Λ (SEQ ID NO: 8) reverse primer sequence S -ATCCATCAGCAATGACACGA^ (SEQ ID NO:9), or InD28432 marker primers:

forward primer sequence S -TGCAGACACCACATGCATAA^ (SEQ ID NO: 10) reverse primer sequence S -ACGCATACACACAGGGACAA^ (SEQ ID NO: 11), or InD2 marker primers:

forward primer sequence S -AACAGACACGTTGCGTCTTG^ (SEQ ID NO: 12) reverse primer sequence S -CTTGCCGCTTAGAGGAGATG^ (SEQ ID NO: 13), or InD14 marker primers:

forward primer sequence S -CCACTCTGAAAATCCCAAGC^ (SEQ ID NO: 14) reverse primer sequence S -ACCAGTTAAGTCACGCTCAAA^ (SEQ ID NO: 15), or RM28466 marker primers:

forward primer sequence 5 Λ -CCG ACGAAGAAGACGAGG AGTAGCC-3 Λ (SEQ ID NO: 16)

reverse primer sequence S -AGGCCGGAGAGCAATCATGTCG^ (SEQ ID NO: 17), or RM28481 marker primers:

forward primer sequence S -GTCAATTAACCATTGCCCATGC^ (SEQ ID NO: 18) reverse primer sequence S -TTCACGTGGGAACTACTCATGC^ (SEQ ID NO: 19), or RM28486 marker primers:

forward primer sequence S -TTCTCTGAATGCCCTGTCTCTCC^ (SEQ ID NO:20) reverse primer sequence S -GGCAAATCAGAACAAGTCTCACC^ (SEQ ID NO:21), The DNAs of brown planthopper-resistant rice varieties or breeding materials are amplified; and if an amplified fragment of 213 bp can be amplified using the primers

RM28438, or an amplified fragment of 221 bp can be amplified using the primers InD28450, or an amplified fragment of 323 bp can be amplified using the primers InD28453, or an amplified fragment of 320 bp can be amplified using the primers InD28432, or an amplified fragment of 241 bp can be amplified using the primer InD2, or an amplified fragment of 397 bp can be amplified using the primers InD14, or an amplified fragment of 85 bp can be amplified using the primers RM28466, or an amplified fragment of 237 bp can be amplified using the primers RM28481 , or an amplified fragment of 161 bp can be amplified using the primers RM28486, this indicates the existence of a brown planthopper resistance major gene locus Bph9 in rice. Therefore, the identification of existence of the Bph9 resistance gene by the molecular marker method provided in the present invention has a very high efficiency, and the method can predict brown planthopper resistance of rice plants and promote the breeding of brown planthopper-resistant rice varieties.

4. Construction of a genomic library of brown planthopper-resistant rice

The preparation of plant high molecular weight genomic DNA is done with reference to the method proposed by Zhang Hongbin et al. (Zhang et al., Preparation of megabase DNA from plant nuclei. Plant J 1995, 7, 175-184). The nuclei of young leaves of the brown planthopper-resistant parent Pokkali (IRGC 108921, containing the brown planthopper resistance gene Bph9, derived from the National Crop Germplasm Preservation Center of the Institute of Crop Science, Chinese Academy of Agricultural Sciences) are extracted, and the genomic DNA is extracted by means of low melting point agarose embedding. The genomic DNA is physically fragmented, the fragmented DNAs are separated by alternating pulsed field electrophoresis using a CHEF Mapper apparatus, and the gel is extracted to recover the DNA fragment between 38 kbp and 48 kbp. The recovered DNA fragment is subjected to end-blunting and phosphorylation and then recovered by pulsed field

electrophoresis. T4 DNA ligase is added to 250 ng recovered DNA fragment and 500 ng pCClFOS (manufactured by the EPICENTRE company) vector and the resulting mixture stands overnight for ligation at 4°C. 10 μΐ ^ ligation reaction solution is added to 25

Maxplax Lambda packaging Extracts (manufactured by the EPICENTRE company) molten on ice, followed by package at 30°C for 90 minutes. Then, 25 Maxplax Lambda packaging Extracts is added for packaging at 30°C for 90 minutes. A bacteriophage diluted buffer solution (Phage Dilution Buffer) is added until the total volume is 1 mL. The mixture is blended gently until uniform. 25 chloroform is added into each tube. The mixture is blended gently until uniform and then stored at 4°C. The successfully-packaged bacteriophage particles are diluted with the bacteriophage diluted solution and then transfected into the host strain

EPI300-T1R (manufactured by the EPICENTRE company) and incubated at 37°C for 20 minutes, and then spread on an LB plate containing 12.5 μg/mL chloramphenicol and cultured overnight at 37°C, and the Copycontrol Fosmid clones are picked. 16 white single bacterial colonies are randomly selected from the plate and cultured, followed by DNA extraction and Notl digestion, and then the lengths of the inserted fragments are determined by pulsed field electrophoresis, and the result shows that the average length of the 16 DNAs is more than 35 kbp and the insertion rate is 100%, which comply with the requirements of the library. A 96-well clon-pool plate is made such that about 100 single clones are randomly selected in each well, 12 plates are made in total and stored at -80°C, and the library construction is completed.

5. Screening of Fosmid genomic library and sequence analysis of Bph9 mapping segment

The Fosmid genomic library is screened using the molecular markers specific to the Bph9 fine mapping interval, the positive clones obtained by screening are subjected to terminal sequencing to determine the overlapping relationship of the positive clones and to finally determine that the two positive clones 544-22 and 19 cover the whole Bph9 fine mapping interval (molecular markers InD2 and RM28466 segments). The complete sequences of the Fosmid clones 544-22 and 19 are subjected to sequencing analysis to finally obtain the complete sequence of the Bph9 mapping interval, i.e., the sequence between the molecular markers InD2 and RM28466, having a length of about 68 kb. The complete sequence is used as a target to search the NCBI database, so as to obtain a homologous sequence of the Japonica rice variety 'Nipponbare' genome within the segment. Gene prediction and annotation is performed by use of FGENESH, and the comparative analysis is performed by use of ClustalW (Table 4).

Table 4. Comparison of the predicted genes of resistant rice and Japonica rice variety 'Nipponbare' within the Bph9 gene-containing segment

predicted genes in Japonica rice predicted genes in Bph9 mapping similarity variety 'Nipponbare' genome segment-containing resistant parent (%) sequence corresponding to Bph9 Pokkali genome sequence

mapping segment

number Predicte quantit Quantit numbe Predicted quantity quantity

d y of y of r function of of exons function amino exons amino

acids acids

gi presump 178 3

-tive

trans- poson

protein

g2 lipoxy922 8 gi lipoxy882 7 95 genase genase

2.1 2.1

chloro- chloro- plast plast

precurso precursor

r

g3

g4 g5 g6

The comparison of the predicted genes shows that the Bph9 mapping region in the resistant parent Pokkali (IRGC 108921) has a total of eight predicted genes, of which four genes are transposon-related proteins (Table 4 Pokkali predicted genes g3, g4, g6 and g7), one is a gene with short encoding sequence (Table 4 Pokkali predicted gene g5), one is a metabolism-related gene (Table 4 Pokkali predicted gene gl Lipoxygenase), and two are resistance genes (Table 4 Pokkali predicted genes g2 and g8). According to the gene nature, so far it is believed that the infection processes of piercing-sucking insects and pathogenic bacteria to rice are similar, and it is possible that the mechanism of resistance to

piercing-sucking insects in rice is the same as that to pathogenic bacteria. Therefore, the foregoing two resistance genes (Table 4 Pokkali predicted genes g2 and g8) are used as candidate genes for the brown planthopper resistance gene Bph9, but the expression of one predicted resistance gene cannot be detected (Table 4 Pokkali predicted gene g2), and finally the other resistance gene (Table 4 Pokkali predicted gene g8) is used as the key candidate gene for Bph9 and has a sequence shown as SEQ ID NO: 1.

6. Full-length cDN A obtained by RACE

Using a template which is the reverse transcription product of total RNA from leaf sheaths of the brown planthopper-resistant parent Pokkali (IRGC 108921, containing the brown planthopper resistance gene Bph9, derived from the National Crop Germplasm

Preservation Center of the Institute of Crop Science, Chinese Academy of Agricultural Sciences), and primers (TPT203, S -GATCTCAGTGTGGGGAATGG^ (SEQ ID NO:26), RR376-1, 5 Λ -AGAGCGAC AAGGGC AGATAA-3 Λ (SEQ ID NO:27)) designed according to the result of gene prediction, a cDNA sequence of the candidate gene is amplified. Primers are designed according to the sequence, the 5 '-end and 3 '-end sequences of the candidate gene are obtained using a 573 '-end Full RACE kit from the TaKaRa company, the transcription initiation site and transcription termination site of the candidate gene are determined, and a full-length cDNA sequence of the gene is spliced. Primers are re-synthesized according to the full-length cDNA sequence, and the full-length cDNA of Bph9 is obtained by amplification and has a nucleotide sequence shown as SEQ ID NO: 2, in which the No. 1-64 bp are a 5UTR untranslated region and the No. 3686-4042 bp are a 3UTR untranslated region.

7. After cloning of the rice brown planthopper resistance gene Bph9, according to the genome sequence and cDNA sequence of the Bph9 gene, multiple pairs of primers of SSR markers or STS markers can be designed. According to the genome sequence where the Bph9 gene is located and the comparison of the genome sequence to the corresponding genome sequences of the sequenced rice varieties 9311 and Nipponbare, InDel marker IR2 (forward primer sequence 5 Λ -AGGATGGGG AGAAGAAGACG-3 Λ (SEQ ID NO:22), reverse primer sequence S -GTGTTCCTTGTCGGGTGTA^ (SEQ ID NO:23)) can be developed for selective breeding of resistant rice carrying the brown planthopper resistance gene Bph9, and the length of the amplified fragment using IR2 is 228 bp (Fig. 5). The genomic DNAs of the resistant rice, susceptible varieties and offspring plants obtained by hybridization and backcross thereof are extracted and amplified by PCR using the primers designed based on the Bph9 gene sequence, and the molecular marker detection is performed by means of polyacrylamide gel electrophoresis. Among the hybrid offspring plants, the plants having the same PCR bands as the resistant rice (the amplification product contains the fragment of 228 bp) are the selected plants which contain the Bph9 gene, and the plants are subjected to continuous backcross and agronomic trait selection to breed rice with resistance to brown planthopper.

Example 2. Functional verification and use of the Bph9 gene

1 . Construction of a genetic transformation vector

( 1 ) Construction of a transformation vector containing the promoter, complete

ORF and transcriptional termination region of the Bph9 gene. The vector used is

pCAMBIA1301 (purchased from the Center for the Application of Molecular Biology to International Agriculture, Australia), and the vector pCAMBIA1301 is double-digested with enzymes Sail and EcoRI to ligate foreign fragments to the Sail and EcoRI sites of the vector pCAMBIA1301.

According to the screening and sequencing results of the Fosmid genome library, the 3026 bp fragment which is obtained by double digestion of the Fosmid clone where the Bph9 gene is located with Sail and Ncol serves as the promoter region of the Bph9 gene (there is a translation initiation codon of the Bph9 gene at the Ncol site).

A 3346 bp fragment is obtained by double digesion of the full-length cDNA clone of the Bph9 gene with Ncol and Xhol, which comprises most of the ORF region of the Bph9 gene and also comprises most of the No. 3 exon of the gene (an Xhol site is located at the terminal of the No. 3 exon). The Bph9 genome has a sequence length of 15628 bp and has two introns and three exons. The ORF length of the Bph9 genome is 3621 bp, there is an Xhol site at 3344 bp, and also the Xhol site is located at the terminal of the No. 3 exon. A 1291 bp fragment is obtained by double digestion of the Fosmid clone where the Bph9 gene is located with Xhol and EcoRI, and the fragment comprises the part behind the Xhol site of the No. 3 exon and the transcriptional termination region of the Bph9 gene. A 3346 bp fragment which is obtained by double digestion of the full-length cDNA clone of the Bph9 gene with Ncol and Xhol, and a 1291 bp fragment which is obtained by double digestion of the Fosmid clone where the Bph9 gene is located with Xhol and EcoRI are ligated to the Ncol and EcoRI sites of the pGEM T easy vector by means of three-fragment ligation. A 4637bp fragment which is obtained by double digestion with Ncol and EcoRI comprises the complete ORF and transcriptional termination region of the Bph9 gene.

The Bph9 gene promoter region (3026bp fragment) obtained by double digestion with Sail and Ncol, and the Bph9 gene complete ORF and transcriptional termination region (4637bp fragment) obtained by double digesion with Ncol and EcoRI are are ligated to the Sail and EcoRI sites of the vector pCAMBIA1301 by means of three-fragment ligation. After verification by sequencing, the resulting vector is the Bph9 gene genetic transformation vector (using the promoter region, complete ORF and transcriptional termination region of the gene), and is introduced into Agrobacterium tumefaciens EHA105 by electroporation. The monoclonal population is picked for expanding culture; and after verification by PCR using Bph9 gene-specific primers (RSP1 : S -AGGGCTACCTCATTGTGCTG^ (SEQ ID NO:24), PCR1 : S -CCTTTTCGCTTCGGTAGACA^ (SEQ ID NO:25), an equal volume of 50% glycerol is added and mixed thoroughly, and the resulting mixture is preserved at -70°C.

(2) Construction of a genome complementary vector of the Bph9 gene

The backbone vector used is pCAMBIA1301 (purchased from the Center for the

Application of Molecular Biology to International Agriculture, Australia), and the GFP (green fluorescent protein) gene is ligated to the Ncol and Pmll sites of the vector pCAMBIA1301 to replace the GUS reporter gene on the vector pCAMBIA1301, forming a vector

pCAMBIA1301 (GFP). According to the screening and sequencing results of the Fosmid genome library, a 2366 bp fragment is obtained by double digestion of the Fosmid clone where the Bph9 gene is located with Sail and Kpnl, and a 13257 bp fragment is obtained by double digestion of the Fosmid clone where the Bph9 gene is located with Kpnl and EcoRI; and the two fragments comprise the genome sequence where the Bph9 gene is located (containing the promoter region, gene encoding region and transcriptional termination region), and the two fragments are ligated sequentially to the Sail and Kpnl sites and the Kpnl and EcoRI sites of the vector

pCAMBIA1301 (GFP) to generate a genome complementary vector of the Bph9 gene. The genome complementary vector is introduced into Agrobacterium tumefaciens EHA105 by electroporation. The monoclonal population is picked for expanding culture; and after verification by PCR using Bph9 gene-specific primers IR2 (forward primer sequence

5 Λ -AGGATGGGGAGAAGAAGACG-3 Λ (SEQ ID NO:22) and reverse primer sequence S -GTGTTCCTTGTCGGGTGTA^ (SEQ ID NO:23)), an equal volume of 50% glycerol is added and mixed thoroughly, and the resulting mixture is preserved at -70°C.

2 . Genetic transformation

By genetic transformation mediated by Agrobacterium tumefaciens EHA105 (Hiei et al., 1994, Efficient transformation of rice (Oryza sativa L.) mediated by Agrobacterium and sequence analysis of the boundaries of the T-DNA. Plant Journal 6:271-282), the genetic transformation vector containing the Bph9 gene ( the promoter, complete ORF and

transcriptional termination region transformation vector; and genome complementary vector) is introduced into a brown planthopper-susceptible common rice variety Kasalath (purchased from the National Rice Germplasm Bank or the International Rice Research Institute).

3 . Verification of transgene function of the Bph9 gene

15 positive transgenic plants are obtained using the genetic transformation vector containing the promoter, complete ORF and transcriptional termination region of the Bph9 gene (named as POK1 , POK2, POK3, POK4, POK5, POK6, POK7, POK8, POK9, POK10, POK11 , POK12, POK13, POK14 and POK15 respectively). After seed harvest, resistance identification is performed in the Ti-generation Bph9 transgenic plants by the standard seedbox screening technique. As shown in Fig. 4, the identification of brown planthopper resistance is performed in the positive transgenic lines POK1 , POK2 and POK3. In the offsprings of rice transgenic plants, the foreign genes will segregate, which conforms to Mendel's law of segregation, and 1/4 of single copy transgenic Ti-generation plants do not contain foreign genes. In this example, during the resistance identification of Ti -generation transgenic plants of POK1 , POK2 and POK3 by the standard seedbox screening technique, firstly the Ti-generation plants of the transgenic lines POK1 , POK2 and POK3 are sowed separately, the DNAs of the Ti-generation transgenic plants of the transgenic lines POK1, POK2 and POK3 are extracted respectively when the seedlings have grown to the one-euphylla one-apical bud stage, and positive plants are identified from the Ti -generation transgenic plants by using the Bph9 gene-specific primers (RSPl : S -AGGGCTACCTCATTGTGCTG^ (SEQ ID NO:24), PCRl : S -CCTTTTCGCTTCGGTAGACA^ (SEQ ID NO:25)) and then transferred to a new bread box together with the susceptible parent TNI, susceptible transgenic recipient material Kasalath and brown planthopper-resistant parent Pokkali; 2-3 -year old brown planthopper nymphae are inoculated at a ratio of 8 nymphae/seedling when the seedlings have grown to the two-euphylla one-apical bud stage, and finally the identification of brown planthopper resistance is performed. As shown in Fig. 4, the identification result shows that, 7 days after exposure to brown planthopper, the whole plants of the susceptible control variety TNI and susceptible transgenic recipient material Kasalath are dead, while the plants of the brown planthopper-resistant parent Pokkali grow healthily without leaf damage. The positive transgenic plants POK1, POK2 and POK3 obtained using the genetic transformation vector containing the Bph9 gene also grow healthily without leaf damage and have resistance scores of 2-3, which indicates that the Bph9 gene has a function of resistance to brown planthopper. Therefore, the brown planthopper resistance gene Bph9 can be applied in rice as well as rice seeds to breed rice varieties having brown planthopper resistance.

20 positive transgenic plants are obtained using the genome complementary vector of the Bph9 gene (named as PGK1, PGK2, PGK3, PGK4, PGK5, PGK6, PGK7, PGK8, PGK9, PGK10, PGK11, PGK12, PGK13, PGK14, PGK15, PGK16, PGK17, PGK18, PGK19 and PGK20 respectively). For a portion of the To-generation transgenic plants, the identification of brown planthopper resistance is performed at the tillering stage. The materials PGK1, PGK2 and susceptible control variety TNI (Taichung local No. 1) are transplanted into a planting pot, the plants are transplanted diagonally, the four plants form a square-like shape (Fig. 5) after transplantation, and 100 2-3 -year old brown planthopper nymphae are inoculated after the plants have entered the tillering stage, followed by identification of brown planthopper resistance. As shown in the Fig. 5, the identification result shows that 28 days after exposure to brown planthopper, the whole plants of susceptible control variety TNI are dead, and the positive transgenic plants PGK1 and PGK2 which are obtained using the genome

complementary vector of the Bph9 gene grow healthily without leaf damage, and the result is the same as that of resistance identification when the genetic transformation vector containing the promoter, complete ORF and transcriptional termination region of the Bph9 gene is used, indicating that the Bph9 gene has a function of resistance to brown planthopper. Example 3. Identification of molecular markers

1 Materials and Methods

1.1 Materials: brown planthopper-resistant parent Pokkali (IRGC 108921 , containing the brown planthopper resistance gene Bph9), brown planthopper-susceptible rice variety Yangdao No. 6 (93-11) and F 23 lines constructed by Pokkali/Y angdao No. 6 hybridization, both 93-11 and Pokkali being from the National Crop Germplasm Preservation Center of the Institute of Crop Science, Chinese Academy of Agricultural Sciences.

Molecular marker primers: InD2, RM28466, RM28438, InD28450, InD28453, InD14, InD28432, RM28481 and RM28486, having nucleotide sequences shown as SEQ ID NOs: 4-21 respectively.

1.2 Methods

Genomic DNAs of rice samples are extracted by the CTAB method. The sample DNAs are amplified using primers InD2, RM28466, RM28438, InD28450, InD28453, InD14,

InD28432, RM28481 and RM28486 respectively. A 10 μΐ system. The 10 μΐ reaction system comprises: lOxPCR buffer, 1.0 μΐ; 10 mM dNTPs, 0.1 μΐ; 10 μΜ primers, 0.4 μΐ; 5 U/μΙ Taq DNA polymerase, 0.2 μΐ and 50 ng DNA template. The amplification reaction takes place on a Bioer PCR instrument: 94°C 4 min, 94°C 30 s, 55°C 30 s, 72°C 40 s, 32 cycles, 72°C 5 min. The product of amplification is separated using 8% of Native-PAGE, and the map is read and analyzed by silver staining using silver nitrate after electrophoresis.

2 Results: with the foregoing method, the rice varieties Pokkali, Yangdao No. 6 and 24 F 23 lines constructed by Pokkali/Y angdao No. 6 hybridization are amplified respectively. The results show that among the F 23 lines constructed by Pokkali/Y angdao No. 6 hybridization, all the F 23 lines from which the corresponding 241 bp fragment, 85 bp fragment, 213 bp fragment, 221 bp fragment, 323 bp fragment, 397 bp fragment, 320 bp fragment, 237 bp fragment and 161 bp fragment can be amplified using the molecular markers InD2, RM28466, RM28438, InD28450, InD28453, InD14, InD28432, RM28481 and RM28486 respectively show resistance to brown planthopper (as shown in the original Fig. 2, No. 2, No. 3, No. 5, No. 6, No. 8, No. 10, No. 12, No. 14, No. 15, No. 18, No. 19, No. 20, No. 21 and No. 23 materials from which the 161 bp specific fragment can be amplified using the molecular marker

RM28486), and the results are consistent with the that of the positive control Pokkali. However, all other F 23 lines constructed by Pokkali/Y angdao No. 6 hybridization, from which the above specific fragments cannot be amplified, show susceptibility to brown planthopper (as shown in the original Fig. 2, No. 1, No. 4, No. 7, No. 9, No. 11, No. 13, No. 16, No. 17, No. 22 and No. 24 materials from which the 161 bp specific fragment cannot be amplified using the molecular marker RM28486). Accordingly, it is shown that the molecular marker method provided in the invention can accurately screen rice varieties containing the brown planthopper resistance gene Bph9 and thus greatly increase the breeding efficiency.

Example 4. Molecular marker-assisted selection of brown planthopper-resistant rice having the Bph9 gene

In this example, the molecular marker-assisted selective breeding of the brown planthopper-resistant rice Luoyang No. 9 carrying the Bph9 gene is performed using the foregoing molecular markers, and specifically, it is implemented as follows: a brown planthopper-resistant parent Pokkali (IRGC 108921, containing brown planthopper resistance gene Bph9) is hybridized with a brown planthopper-susceptible rice variety Yangdao No. 6 (93-11) to obtain F ls followed by backcross using the variety Yangdao No. 6, the resulting BCiFi is screened using the Bph9-linked molecular markers (RM28438, RM28486), and the screened BCiFi containing the brown planthopper resistance gene Bph9 is back-crossed to the variety Yangdao No. 6 to obtain BC 2 Fi; the resulting BC 2 Fi is screened using the Bph9-linked molecular markers (RM28438, RM28486), and the screened BC 2 Fi containing the brown planthopper resistance gene Bph9 is back-crossed to the variety Yangdao No. 6 to obtain BC 3 F 1 ; the resulting BC 3 F 1 is screened using the Bph9-linked molecular markers (RM28438, RM28486), and the screened BC 3 F 1 containing the brown planthopper resistance gene Bph9 is back-crossed to the variety Yangdao No. 6 to obtain BC 4 F 1 ; the resulting BC 4 F 1 is screened using the Bph9-linked molecular markers (RM28438, RM28486), and the screened BC 4 F 1 containing the brown planthopper resistance gene Bph9 is back-crossed to the variety Yangdao No. 6 to obtain BC 5 F 1 ; the resulting BC 5 F 1 is screened using the Bph9-linked molecular markers (RM28438, RM28486), and the screened BC 5 F 1 containing the brown planthopper resistance gene Bph9 is back-crossed to the variety Yangdao No. 6 to obtain BC 6 Fi; the resulting BC 6 Fi is screened using the Bph9-linked molecular markers (RM28438, RM28486), and the screened BC 6 Fi containing the brown planthopper resistance gene Bph9 is

back-crossed to the variety Yangdao No. 6 to obtain BC 7 F 1 ; and the resulting BC 7 F 1 is screened using the Bph9-linked molecular markers (RM28438, RM28486) to obtain BC 7 F 1 containing the Bph9 gene, genome -wide scanning is performed using the molecular markers (see Table 5), BC 7 F 1 which differs only in the brown planthopper resistance gene Bph9 locus from the variety Yangdao No. 6 and in which all other loci are replaced with the background of the variety Yangdao No. 6 are selected for generation-adding breeding, Yangdao No. 6/Pokkali (IRGC 108921)//Y angdao No. 6 BC 7 F 2 which is homozygous in the brown planthopper resistance gene Bph9 locus is screened using the Bph9-linked molecular markers (RM28438, RM28486) and subjected to generation-adding breeding; this material is identical in agronomic trait phenotype to the variety Yangdao No. 6 but contains the brown planthopper resistance gene Bph9, and is temporarily named as Luoyang No. 9. By identification through the standard seedbox screening technique, identification at the near-tillering stage and identification at the maturity stage using brown planthopper populations in the farm fields in Wuhan city, it is confirmed that the material is resistant to brown planthopper (see Fig. 7). Also, the

identification through the standard seedbox screening technique is performed using brown planthopper biotype I, biotype II and biotype III, and the results show that, as compared to obvious death of the susceptible variety TNI and recipient parent Yangdao No. 6, the cultivar Luoyang No. 9 (having the genetic background of Yangdao No. 6 and carrying the brown planthopper resistance gene Bph9) survives 7 days after exposure to insects, and the plants grow healthily (Fig. 8). By the identification at the near-tillering stage and identification at the maturity stage using the brown planthopper populations in the farm fields in Wuhan city, it is confirmed that the cultivar Luoyang No. 9 is resistant to brown planthopper (see Fig. 9, Fig. 10). So far, the cultivar Luoyang No. 9 has been declared for rice variety rights.

For any one of the molecular markers in Table 5, the banding pattern of individual plant is recorded as 1 if identical to that of the brown planthopper-resistant parent Pokkali (IRGC 108921), recorded as 2 if identical to that of the parent Yangdao No. 6 (93-11), and recorded as 3 if integrating the banding patterns of the two parents. The result of molecular marker screening shows that BC7F1 differs only in brown planthopper resistance gene Bph9 locus (interval of RM28481 and RM28438) from the variety Yangdao No. 6, and all other loci of BC7F1 are replaced by the genetic background of the variety Yangdao No. 6.

Table 5. Results of genome-wide scanning in rice varieties using the following molecular markers

Physical location using

Molecular Pokkali (IRGC Yangdao No. 6

Nipponbare as reference BC 7 F 1 marker 108921) (93-11)

sequence

Chr. l

RM6433 2971405 1 2 2

RM243 7970722 1 2 2

RM140 12300716 1 2 2

RM10957 16108025 1 2 2

RM11033 18673601 1 2 2

RM 11099 20059015 1 2 2 RM11118 20447469 1 2 2

RM 11225 22237464 1 2 2

RM488 24804715 1 2 2

RM 11409 25870356 1 2 2

RM8096 31363239 1 2 2

Chr.2

RM475 92.5cm 1 2 2

RM279 2882052 1 2 2

RM71 8760433 1 2 2

RM424 11389704 1 2 2

RM300 13190528 1 2 2

RM13581 23861787 1 2 2

RM13622 24927509 1 2 2

RM530 30532198 1 2 2

RM208 35135783 1 2 2

RM207 35369336 1 2 2

RM266 37639550 1 2 2

RM48 190.2CM 1 2 2

RM423 28.7 (-) CM 1 2 2

Chr.3

RM1284 10620093 1 2 2

RM15077 15217175 1 2 2

RM15151 15842011 1 2 2

RM85 19541020 1 2 2

RM411 21385364 1 2 2

RM 15466 23374559 1 2 2

RM15504 23829001 1 2 2

RM15585 25003923 1 2 2

RM15861 29784121 1 2 2

RM143 34201074 1 2 2

RM468 36913809 1 2 2

RM200 38573411 1 2 2

RM514 39644287 1 2 2

RM148 40276298 1 2 2 RM448 189.6CM 1 2 2

Chr.4

RM 16603 11493949

1 2 2

RM16616 12100013 1 2 2

RM3785 24222926 1 2 2

RM2441 28020850 1 2 2

RM303 28540846 1 2 2

Chr.5

592 2796876 1 2 2

RM3322 4203747 1 2 2

RM169 7397690 1 2 2

RM 18299 12564581 1 2 2

RM6229 13472990 1 2 2

RM18353 13873673 1 2 2

RM1127 15879947 1 2 2

RM164 19196472 1 2 2

RM18877 23496587 1 2 2

RM 18926 24335996 1 2 2

Chr.6

RM588 1611442 1 2 2

RM527 9874150 1 2 2

RM7311 10889488 1 2 2

RM 19994 14165857 1 2 2

RM2229 15578596 1 2 2

RM20023 15620125 1 2 2

RM20037 15808584 1 2 2

RM20073 16459700 1 2 2

RM20107 17517746 1 2 2

RM3207 17734772 1 2 2

RM3 19499320 1 2 2

RM528 26172237 1 2 2

RM51 163.2-163.2 (-) CM 1 2 2

RM170 2.2-7.4 (-) CM 1 2 2

Chr.7 RM180 5734495 1 2 2

RM21211 6413217 1 2 2

RM21327 8898096 1 2 2

RM21364 10285970 1 2 2

RM21414 11992116 1 2 2

RM21560 16937298 1 2 2

RM21842 22723145 1 2 2

RM478 25896945 1 2 2

RM22120 28314716 1 2 2

RM125 24.8-24.8 (-) CM 1 2 2

Chr.8

RM3778 3476633 1 2 2

RM22661 7896677 1 2 2

RM344 9778801 1 2 2

RM7267 10186809 1 2 2

RM150 25220872 1 2 2

RM6070 26319660 1 2 2

RM264 29855476 1 2 2

RM44 60.9-69 (-) CM 1 2 2

Chr.9

RM23671 640720 1 2 2

RM23676 727784 1 2 2

RM23753 3127162 1 2 2

RM444 5925016 1 2 2

RM3769 11747444

1 2 2

RM566 14651176 1 2 2

RM108 19304279 1 2 2

RM189 22094561 1 2 2

RM285 1.8-1.8 (-) CM 0 2 2

Chr. lO

RM24904 860945 1 2 2

RM6179 2566362 1 2 2

RM25022 3570052 1 2 2

RM7402 4434461 1 2 2 RM228 21795147 1 2 2

Chr. l l

RM3339 4120770 1 2 2

RM26409 9121438 1 2 2

RM26638 14706978 1 2 2

RM287 16610716 1 2 2

RM224 21849538 1 2 2

RM7221 26421766 1 2 2

RM27322 27551898 1 2 2

Chr.12

RM27442 753705 1 2 2

RM8215 1585845 1 2 2

RM6296 3200705 1 2 2

RM27590 3398200 1 2 2

RM27683 4599717 1 2 2

RM27879 9277822 1 2 2

RM27971 12284083 1 2 2

RM28481 1 2 3

RM28438 1 2 3

RM7102 13258404 1 2 2

RM2972 19208049 1 2 2

RM19 20.9-20.9 (-) CM 1 2 2