Application of Rice Disease-Resistant Related Gene OsGT43G and Its Encoded Protein

Abstract

The present invention discloses the application of a rice disease-resistant related gene OsGT43G and its encoded protein, belonging to the technical field of rice genetic engineering. The present invention discloses the application of a rice OsGT43G gene in regulating the resistance of rice to bacterial blight. The nucleotide sequence of the rice OsGT43G gene is shown in SEQ ID NO:1, and the amino acid sequence of the protein encoded by it is shown in SEQ ID NO:2. The OsGT43G gene provided by the present invention can improve the resistance of rice to Xanthomonas oryzae pv. oryzae. Overexpression of this gene in rice can significantly improve the resistance level of rice to bacterial blight, and knocking out the OsGT43G gene significantly reduces the resistance of rice to Xanthomonas oryzae pv. oryzae. Therefore, the rice OsGT43G gene can be applied to the genetic engineering and breeding of crops, and has good application prospects in cultivating disease-resistant rice varieties, laying an important foundation for rice resistance breeding.

Description

Technical Field

[0001] The present invention relates to the technical field of rice genetic engineering, and particularly to the application of a rice disease-resistant related gene OsGT43G and its encoded protein. Background Art

[0002] Rice (Oryza sativa L.) is one of the most important food crops in the world, and about half of the global population takes rice as the staple food. The safe production of rice is an important factor affecting food security. Bacterial blight is one of the three major traditional diseases of rice, and its occurrence will affect the rice yield and rice quality. In the past 20 years, breeders have gradually paid less attention to bacterial blight, which has laid a hidden danger for the recurrence of bacterial blight, and it is necessary to strengthen the attention to the breeding of rice varieties resistant to bacterial blight. The most fundamental way to solve the disease resistance of crops is to cultivate disease-resistant varieties. With the development of biotechnology, positive regulatory factors or genes of resistance can be directly used to improve plant disease resistance. However, the lack of resistance resources is still the key factor restricting the cultivation of disease-resistant varieties. Long-term production practice has proved that breeding rice varieties resistant to diseases by identifying and using broad-spectrum resistance genes has become an effective and economical strategy for disease control.

[0003] Excavating new genetic resources for resistance to bacterial blight, clarifying the molecular mechanism of resistance, and cultivating new high-quality rice varieties resistant to bacterial blight are of great significance for ensuring the safe production and sustainable development of rice. Summary of the Invention

[0004] The purpose of the present invention is to provide the application of a rice disease-resistant related gene OsGT43G and its encoded protein to solve the problems existing in the above-mentioned prior art. The OsGT43G gene provided by the present invention can improve the resistance of rice to Xanthomonas oryzae pv. oryzae, and has a good application prospect in the cultivation of disease-resistant rice varieties. The present invention has laid an important foundation for rice resistance breeding.

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] The present invention provides an application of a rice OsGT43G gene in regulating the resistance of rice to bacterial blight, and the nucleotide sequence of the rice OsGT43G gene is as shown in SEQ ID NO:1.

[0007] Further, the amino acid sequence of the protein encoded by the rice OsGT43G gene is as shown in SEQ ID NO:2.

[0008] Further, by up-regulating the expression level of the rice OsGT43G gene, the resistance of rice to bacterial blight is improved.

[0009] Furthermore, the rice OsGT43G gene was inserted into an overexpression vector and transferred into a rice receptor material to improve the resistance of rice to bacterial blight.

[0010] Furthermore, by downregulating the expression level of the rice OsGT43G gene, the resistance of rice to bacterial blight was reduced.

[0011] Furthermore, a knockout vector of the rice OsGT43G gene was constructed using the CRISPR / Cas9 method, and the knockout vector was transferred into a rice receptor material to reduce the resistance of rice to bacterial blight.

[0012] Furthermore, the variety of the rice is Zhonghua 11.

[0013] The present invention also provides an application of the rice OsGT43G gene in the breeding of rice resistant to bacterial blight. The nucleotide sequence of the rice OsGT43G gene is shown in SEQ ID NO:1, and the amino acid sequence of the protein encoded by it is shown in SEQ ID NO:2.

[0014] The present invention also provides a method for improving the resistance of rice to bacterial blight, including the step of upregulating the expression level of the rice OsGT43G gene; the nucleotide sequence of the rice OsGT43G gene is shown in SEQ ID NO:1.

[0015] Furthermore, the rice OsGT43G gene was inserted into an overexpression vector and transferred into a rice receptor material to improve the resistance of rice to bacterial blight.

[0016] The present invention discloses the following technical effects:

[0017] By constructing overexpression and gene knockout vectors of the rice OsGT43G gene, the overexpression and knockout vector plasmids were transferred into a rice receptor material through Agrobacterium-mediated transformation. Positive plants were detected by fluorescence quantitative PCR and sequencing analysis. Disease resistance analysis was performed on the obtained positive transgenic plants. The results showed that the OsGT43G gene could improve the resistance of rice to Xanthomonas oryzae pv. oryzae. Overexpression of this gene in rice could significantly improve the resistance level of rice to bacterial blight, and knockout of the OsGT43G gene significantly reduced the resistance of rice to Xanthomonas oryzae pv. oryzae. Therefore, the rice OsGT43G gene can be applied to genetic engineering breeding of crops and has good application prospects in cultivating disease-resistant rice varieties, laying an important foundation for rice resistance breeding. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0019] Figure 1 Results of the analysis of the expression pattern of OsGT43G in wild-type ZH11 after infection with Xanthomonas oryzae pv. oryzae by real-time fluorescence quantitative PCR; Treatment with H 2 O was used as a control for inoculation with Xanthomonas oryzae pv. oryzae and recorded as 0 h; * represents a significant difference compared with the control (*, P < 0.05, **, P < 0.001), and the statistical method was T-test;

[0020] Figure 2 Detection of the expression level of OsGT43G in OsGT43G overexpressing transgenic rice by real-time fluorescence quantitative PCR; "ZH11" represents the wild type, * represents a significant difference compared with the wild type (*, P < 0.05, **, P < 0.001), and the statistical method was T-test;

[0021] Figure 3 Target sequence information of the first exon region of the OsGT43G gene (A) and the editing effect of the target sequence of the knockout transgenic rice (B);

[0022] Figure 4 Detection of the expression levels of defense response genes in OsGT43G overexpressing and knockout transgenic rice by real-time fluorescence quantitative PCR; A: PR1a; B: PR10; * represents a significant difference compared with the wild type (*, P < 0.05, **, P < 0.001), and the statistical method was T-test;

[0023] Figure 5 Detection of the disease resistance of OsGT43G gene overexpressing and knockout transgenic rice; A: Phenotype photos of transgenic rice inoculated with African strain AXO1947; B: Statistical chart of lesion lengths of transgenic rice inoculated with African strain AXO1947; C: Phenotype photos of transgenic rice inoculated with local Guangxi strain type IX; D: Statistical chart of lesion lengths of transgenic rice inoculated with local Guangxi strain type IX. Detailed implementation manners

[0024] The various exemplary implementation manners of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0025] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0026] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0027] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0028] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0029] The present invention provides an application of a rice OsGT43G gene and its encoded protein in regulating the resistance of rice to bacterial blight. It is obtained from rice transcriptome sequencing. The CDS nucleotide sequence of the rice OsGT43G gene is shown as SEQ ID NO: 1; the amino acid sequence of its encoded protein is shown as SEQ ID NO: 2.

[0030] The present invention first used transcriptome sequencing analysis to screen the OsGT43G gene in rice wild type ZH11 that responds to the African strain AXO1947 of Xanthomonas oryzae pv. oryzae, indicating that OsGT43G may be involved in regulating the resistance of rice to Xanthomonas oryzae pv. oryzae. To verify this hypothesis, the present invention used real-time fluorescence quantitative PCR to detect the expression of OsGT43G in wild type ZH11 after inoculation with the African strain AXO1947 of Xanthomonas oryzae pv. oryzae, and found that the expression of OsGT43G was down-regulated at 24 h and 48 h after infection with Xanthomonas oryzae pv. oryzae, indicating that Xanthomonas oryzae pv. oryzae can inhibit the expression of OsGT43G.

[0031] The present invention also provides the application of the above gene in cultivating rice resistant to bacterial blight. By overexpressing the OsGT43G gene in rice, the bacterial blight resistance of rice is improved, and a new rice variety with high resistance to bacterial blight is cultivated.

[0032] To facilitate the understanding of the present invention, the present invention will be more comprehensively described below in conjunction with embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosed content of the present invention more thorough and comprehensive.

[0033] Example 1 Real-time fluorescence quantitative PCR analysis of the response of OsGT43G to Xanthomonas oryzae pv. oryzae

[0034] 1. Primer design for real-time quantitative PCR

[0035] The nucleotide sequence of the cDNA reading frame of rice OsGT43G is shown in SEQ ID NO:1:

[0036] >LOC_Os10g13810

[0037]

[0038] The amino acid sequence encoded by rice OsGT43G is shown in SEQ ID NO:2:

[0039] >LOC_Os10g13810

[0040] MAAPPCPPRRPISAPCFLLCFLLGFVAGLFPFAHRHLHLDLHLPLPPPATAILVREDPPSVVVDVDTPLPAAAEERKLLLVVTPTRARPLQAYYLRRLAHTLRLAPSPLLWLVVESGAATRDTAALLRGCGVMYRHLSSPVPDAPQDRPRRRGRRQDRPAVDSRARQRNTALDHIEHHRLHGIVYFADEDNVYSLDLFYHLRDIRSFGTWPVATLAPGKSKTILQGPVCEGSRVVGWHTTDRSKNQRRFHVDMSGFAFNSSKLWDAKNRGHQAWNYIRQLDTAKEGFQETAFIEQLVEDETHME GVPPGCSKIMNFHLHLEDKNAIYLNGWQTTQNLDVIIPLKKEARPLL*(SEQ ID NO:2).

[0041] Design the following real-time quantitative PCR primers according to the nucleotide sequence of OsGT43G:

[0042] OsGT43G-q-F:CTTTGGGACGCCAAGAAC(SEQ ID NO:3);

[0043] OsGT43G-q-R:GGTTTGCCACCCGTTCAG(SEQ ID NO:4).

[0044] 2. Material culture and infection with Xanthomonas oryzae pv. oryzae

[0045] (1) The experimental rice material is the rice wild type ZH11, which is a susceptible variety to Xanthomonas oryzae pv. oryzae. Plant the ZH11 material in the field until the tillering stage.

[0046] (2) The tested Xanthomonas oryzae pv. oryzae strain is the African AXO1947 strain. Culture the Xanthomonas oryzae pv. oryzae AXO1947 (preserved in the laboratory of Guangxi University) on PSA solid medium at 28 °C, and then adjust the OD of the Xanthomonas oryzae pv. oryzae with sterilized water 600To 0.5; The Xanthomonas oryzae pv. oryzae was inoculated into the leaves of ZH11 at the tillering stage by the injection method. The rice leaves at 0 h, 24 h, and 48 h after inoculation were quickly frozen in liquid nitrogen and stored in a -80 °C refrigerator. Total RNA of rice was extracted using Trizol reagent and reverse transcribed into cDNA for real-time quantitative PCR detection. The results are as Figure 1 shown. After the infection of Xanthomonas oryzae pv. oryzae, the expression of the OsGT43G gene in ZH11 was significantly down-regulated, indicating that this gene plays an important role in the process of resistance to rice bacterial blight.

[0047] Example 2 Construction of OsGT43G overexpression and knockout transgenic rice

[0048] 1. An overexpression vector of OsGT43G was constructed using the PCAMBIA1301 vector in our laboratory, and the expression of OsGT43G was driven by the 35S promoter, specifically as follows:

[0049] (1) The following primers were designed according to the nucleotide sequence of OsGT43G to amplify its CDS sequence:

[0050] OsGT43G-FLAG-F: cttgaccatggtagatctATGGCCGCTCCGCCGTGC (SEQ ID NO:5);

[0051] OsGT43G-FLAG-R: tgtaattcacacggtgaccTAGTAGGGGCCTTGCTTCC (SEQ ID NO:6).

[0052] (2) Total RNA was extracted from the leaves of wild-type ZH11 grown under normal conditions and reverse transcribed into cDNA. Using the cDNA as a template, the rice OsGT43G gene was amplified using the high-fidelity DNA polymerase Max Master Mix. The PCR product was detected by 1% agarose gel electrophoresis, and a single DNA band (1053 bp) could be obtained, which was the OsGT43G gene fragment amplified by PCR. The OsGT43G fragment was recovered by agarose gel electrophoresis according to the instructions of the Magen HiPure Gel Pure DNA Kits.

[0053] The PCAMBIA1301 vector was double-digested with BglII and BstEII and the digested products were recovered. According to the instructions of the ClonExpress II One Step Cloning Kit, the above-mentioned OsGT43G gene fragment recovery product was ligated to the PCAMBIA1301 vector by homologous recombination according to the following system to obtain the overexpression vector of OsGT43G (OsGT43G-ox).

[0054] Table 1 Connection System

[0055]

[0056]

[0057] Note: X / Y is calculated according to the formula to obtain the amounts of vector used and insert fragment used. (Calculation formula: Optimal amount of cloning vector used = [0.02 × number of base pairs of cloning vector] ng; Optimal amount of insert fragment used = [0.04 × number of base pairs of insert fragment] ng).

[0058] 2. Construct a knockout vector of OsGT43G using the pYLCRISPR / Cas9Pubi-H vector as follows:

[0059] (1) According to the nucleotide sequence of OsGT43G, select the following target sequence on the first exon:

[0060] Target: CCCGGCTGTTGACAGCCGCG (SEQ ID NO:7).

[0061] Synthesize the following target primers according to the target sequence:

[0062] OsGT43G-gRT1: CCCGGCTGTTGACAGCCGCGgttttagagctagaaat (SEQ ID NO:8);

[0063] OsGT43G-OsU6aT1: CGCGGCTGTCAACAGCCGGGggcagccaagccagca (SEQ ID NO:9).

[0064] (2) Construct the sgRNA expression cassette:

[0065] 1) Take 2 - 5 ng of pYLgRNA-OsU6a plasmid as the template, 0.2 μM each of primers U-F and OsGT43G-OsU6aT1, and 0.1 μM each of gR-R and OsGT43G-gRT1, and use the high-fidelity enzyme Max Master Mix for the first round of PCR reaction. The PCR reaction program is as follows: 25 - 28 cycles: 94°C for 10 s, 58°C for 15 s, 72°C for 20 s. During the amplification process, the sgRNA expression cassette fragment combined with 2 fragments is generated by overlapping PCR. The sequence of primer U-F is as shown in SEQ ID NO:10, and the sequence of primer gR-R is as shown in SEQ ID NO:11;

[0066] U-F: CTCCGTTTTACCTGTGGAATCG (SEQ ID NO:10);

[0067] gR-R: CGGAGGAAAATTCCATCCAC (SEQ ID NO:11).

[0068] 2) Take 1 μl of the first-round PCR product and dilute it 10-fold with ddH 2 O. Take 1 μl as the template. Add Pps-GGL and Pgs-GGR as primers (final concentration 0.15 μM). Use the high-fidelity enzyme Max Master Mix for amplification. The PCR program is: 17 - 20 cycles: 94°C for 10 s, 58°C for 15 s, 72°C for 20 s. The PCR product is detected by 1% agarose gel electrophoresis, and the sgRNA expression cassette is recovered. The sequence of the primer Pps-GGL is shown in SEQ ID NO:12, and the sequence of the primer Pgs-GGR is shown in SEQ ID NO:13;

[0069] Pps-GGL: TTCAGAggtctcTctcgACTAGTATGGAATCGGCAGCAAAGG (SEQ ID NO:12);

[0070] Pgs-GGR: AGCGTGggtctcGaccgACGCGTATCCATCCACTCCAAGCTC (SEQ ID NO:13).

[0071] 3) Assemble the sgRNA expression cassette into the pYLCRISPR / Cas9Pubi-H vector. Perform the digestion-ligation reaction on the pYLCRISPR / Cas9Pubi-H plasmid and the sgRNA expression cassette according to the system shown in Table 2. Use temperature cycling for digestion-ligation: first 3 cycles (37°C for 10 min, 10°C for 5 min, 20°C for 5 min); then 10 cycles (37°C for 3 min, 10°C for 5 min, 20°C for 5 min), and finally 37°C for 5 min. Obtain the ligation product;

[0072] Table 2 Digestion-ligation system

[0073]

[0074] 4) Transform the ligation product in step 3) into DH5α competent cells by heat shock, and identify positive clones through blue-white screening and colony PCR detection to obtain the OsGT43G gene knockout vector.

[0075] Example 3 Obtaining of OsGT43G overexpression and knockout transgenic rice and identification of positive plants

[0076] The overexpression and knockout vector plasmids of OsGT43G obtained in Example 2 were transferred into Agrobacterium tumefaciens EHA105. Through the genetic transformation method mediated by Agrobacterium tumefaciens EHA105, the overexpression and knockout vectors were transformed into the wild-type ZH11 variety to obtain transgenic plants. After PCR detection of the hygromycin gene Hpt and real-time quantitative PCR detection of the expression of OsGT43G, transgenic positive plants OsGT43G-ox-1 and OsGT43G-ox-2 with overexpression of OsGT43G were obtained ( Figure 2 ).

[0077] The following method was used to detect the targeting effect of the OsGT43G gene knockout transgenic rice:

[0078] (1) The DNA of the T0 generation of the OsGT43G gene knockout transgenic rice obtained by the CTAB method was used for PCR amplification of the target sequence in the first exon region of the OsGT43G gene, and the amplification product was sent to Shanghai Sangon Biotech Co., Ltd. for sequencing. The PCR amplification primers for the target sequence in the first exon region of the OsGT43G gene included the upstream primer shown in SEQ ID NO:14 and the downstream primer shown in SEQ ID NO:15.

[0079] OsGT43G-JC-F: AAGCTGCTGCTGGTCGTG (SEQ ID NO:14);

[0080] OsGT43G-JC-R: GGCACCAATGAGTTTCGTG (SEQ ID NO:15).

[0081] (2) The sequencing results were compared with the target sequence, and the success of targeting was identified by judging whether single-base insertions, deletions, mutations, or deletions of several bases occurred at the target site.

[0082] The results are as Figure 3 shown. In the OsGT43G gene knockout transgenic rice osgt43g-1 and osgt43g-2, the target sequences in the first exon region of the OsGT43G gene had 1bp and 4bp base deletions compared with the wild-type WT, respectively, proving that the targeting of the target sequences of the OsGT43G gene knockout transgenic rice was successful.

[0083] Example 4 Expression of OsGT43G-Regulated Disease Resistance-Related Defense Response Genes

[0084] Plant disease resistance is accompanied by the expression of a series of defense response genes. To verify the role of OsGT43G in plant disease resistance, real-time quantitative PCR was used to detect the transcriptional levels of the defense response genes PR1a (RAP-DB accession number: Os07g0129200) and PR10 (RAP-DB accession number: Os12g0555000). The primers and sequences for real-time quantitative PCR detection are shown below:

[0085] PR1a-q-F: CGTGTCGGCGTGGGTGT;

[0086] PR1a-q-R: GGCGAGTAGTTGCAGGTGATG.

[0087] PR10-q-F: GCCATGCCCAAGGTTTGT;

[0088] PR10-q-R: CATCATCCACAGCAGGGTT.

[0089] The experimental results are as Figure 4 shown. After overexpressing the OsGT43G gene in rice, the expression levels of defense response genes such as PR1a and PR10 were significantly upregulated. After reducing the expression of the OsGT43G gene in rice, the expression levels of defense response genes such as PR1a and PR10 were significantly downregulated. This indicates that the OsGT43G gene positively regulates rice disease resistance.

[0090] Example 5 Analysis of Disease Resistance of OsGT43G Gene Overexpressing and Knockout Transgenic Rice

[0091] The positive plants of the gene overexpressing and knockout transgenic offspring obtained in Example 3 were subjected to disease resistance detection. The specific detection method is as follows:

[0092] (1) The African strain AXO1947 and the local Guangxi type IX strain IX2026 of Xanthomonas oryzae pv. oryzae were cultured on PSA solid medium at 28 °C (both are stored in the laboratory of Guangxi University). Subsequently, the OD of Xanthomonas oryzae pv. oryzae was adjusted to 0.5 with sterilized water; 600 to 0.5;

[0093] (2) Dip scissors in the bacterial solution and cut the leaves at 3 - 5 cm from the leaf tips of wild-type ZH11 and OsGT43G gene transgenic rice to complete inoculation;

[0094] (3) Fourteen days after inoculation, the disease resistance of rice was judged by measuring the lesion length; the longer the lesion, the more susceptible the rice, and the shorter the lesion, the more disease-resistant the rice.

[0095] The results are as Figure 5As shown, the results indicate that for the OsGT43G gene overexpressing transgenic rice inoculated with strains AXO1947 and IX2026 respectively, compared with the wild type ZH11, the lesion length is shorter and the disease resistance is enhanced; for the OsGT43G gene knockout transgenic rice inoculated with strains AXO1947 and IX2026 respectively, compared with the wild type ZH11, the lesion length is longer, it is more susceptible to disease, and the disease resistance decreases. It is confirmed that overexpressing the OsGT43G gene can significantly improve the resistance of rice to Xanthomonas oryzae pv. oryzae, while knocking out the OsGT43G gene can significantly reduce the resistance of rice to Xanthomonas oryzae pv. oryzae.

[0096] The embodiments described above are only descriptions of the preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. Application of a rice OsGT43G gene in regulating resistance to bacterial blight of rice, It is characterized in that The rice OsGT43G The nucleotide sequence of the gene is shown in SEQ ID NO: 1; by overexpressing the rice OsGT43G gene, the resistance of rice to bacterial blight is improved.

2. The application according to claim 1, It is characterized in that Insert the rice OsGT43G gene into an overexpression vector and transfer it into rice recipient materials to improve the resistance of rice to bacterial blight.

3. The application according to claim 1, It is characterized in that the variety of the rice is Zhonghua 11.

4. An application of a rice OsGT43G gene in the breeding of rice for resistance to bacterial blight It is characterized in that The rice OsGT43G The nucleotide sequence of the gene is shown in SEQ ID NO:1, and the amino acid sequence of the protein encoded by it is shown in SEQ ID NO:2; by overexpressing the rice OsGT43G gene, the resistance of rice to bacterial blight is improved.

5. A method for improving the resistance of rice to bacterial blight, It is characterized in that Including the step of up-regulating the expression level of a rice OsGT43G gene; the rice OsGT43G gene has a nucleotide sequence as shown in SEQ ID NO:

1.

6. The method according to claim 5, It is characterized in that Insert the rice OsGT43G gene into an overexpression vector and transfer it into rice receptor materials to improve the resistance of rice to bacterial blight.

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