Application of secondary metabolite homovanillic acid of rice
By screening and utilizing rice varieties with high vanillic acid content, and using LOC_Os03g58380 gene to regulate the biosynthesis of high vanillic acid, the problems of brown planthoppers against chemical pesticides and environmental pollution were solved, and efficient and green prevention and control effects were achieved.
Patent Information
- Application Number
- CN202510114136.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-24
- Publication Date
- 2025-06-06
AI Technical Summary
Brown planthoppers are resistant to commonly used chemical pesticides, and the large amount of chemical pesticides are used to cause pollution to the environment. It is difficult for the existing technology to effectively prevent and control rice pests.
By detecting the content of high vanillic acid in rice, selecting rice varieties with high vanillic acid content, and using high vanillic acid as a compound to control brown planthoppers, combining LOC_Os03g58380 gene to regulate the biosynthesis of high vanillic acid, improving or reducing the resistance of rice to brown planthoppers.
It has achieved effective prevention and control of rice pest brown planthoppers through high vanillic acid, and improved the resistance of rice to brown planthoppers, providing technical support for the selection of rice varieties that are resistant to brown planthoppers.
Smart Images
Figure CN120099019A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of biotechnology, and more specifically relates to the application of homovanillic acid, a secondary metabolite of rice. Background Art
[0002] Rice is a grass plant. About half of the world's population eats rice. Rice is grown in parts of Asia, southern Europe, America, and Africa. Rice planthoppers, borers, rice blast, bacterial leaf streak, and bacterial leaf blight are important factors affecting rice yield and quality. Among them, brown planthopper (Nilaparvata lugens ) is one of the important pests that has a serious impact on rice. It mainly affects the normal growth and development of rice by sucking rice sap and spreading diseases. When it occurs seriously, it can lead to a large-scale reduction in rice production or even a complete loss of harvest.
[0003] In order to prevent and control the damage of rice pests, the long-term and large-scale use of chemical pesticides has caused brown planthoppers to develop moderate to high levels of resistance to many commonly used chemical pesticides; at the same time, the large-scale use of chemical pesticides will also cause varying degrees of environmental pollution. The green control of brown planthoppers currently focuses on the application of plant-derived active ingredients and the application of natural enemy insects and microbial pesticides. A large number of studies have shown that plant secondary metabolites have good defense or inhibitory effects on crop diseases and pests. Therefore, screening rice varieties or rice secondary metabolites that are resistant to brown planthoppers is the most economical, efficient and green way to control rice pests.
[0004] Therefore, it is of great significance to explore the plant-derived active ingredients that are resistant to brown planthoppers and to breed highly insect-resistant rice varieties. Summary of the invention
[0005] The present invention aims to provide a compound homovanillic acid capable of preventing and controlling brown planthoppers. The resistance of rice to brown planthoppers can be quickly determined by detecting the content of homovanillic acid in rice, and the brown planthoppers can be prevented and controlled by screening rice with high homovanillic acid content.
[0006] The first object of the present invention is to provide application of homovanillic acid in controlling brown planthopper.
[0007] The second objective of the present invention is to provide an application of the LOC_Os03g58380 gene in regulating the high vanillic acid content in rice or regulating the resistance of rice to brown planthoppers.
[0008] The third object of the present invention is to provide a method for screening rice varieties resistant to brown planthoppers.
[0009] The fourth object of the present invention is a method for controlling brown planthopper.
[0010] The above-mentioned purpose of the present invention is achieved through the following technical solutions:
[0011] Our study found that homovanillic acid is commonly found in the tissues of rice stems, leaf sheaths, leaves, etc. The results of HPLC detection of tissues of different parts of rice varieties such as Luyoumingzhan, Wuxiangsimiao, Zhonghua No. 11 and Nihonbare showed that the content of homovanillic acid in tissues of different parts of rice was different, ranging from 0.2 to 45μg / g. The content of homovanillic acid in leaves was relatively high, ranging from 14 to 45μg / g, and the content of homovanillic acid in stems and leaf sheaths was relatively low, ranging from 0.2 to 10μg / g. The mortality rate of brown planthoppers feeding only on rice leaves for 7 days exceeded 60%, while the mortality rate of brown planthoppers feeding only on rice leaf sheaths or stems for 7 days was less than 20%.
[0012] When the artificial diet fed by brown planthoppers contained 0.5-30 ppm of homovanillic acid, the mortality of brown planthopper nymphs, short-winged and long-winged adults increased by 2.5-260% on the 7th day. This indicates that homovanillic acid, a secondary metabolite of rice, can cause the death of brown planthoppers, and high levels of homovanillic acid (above 15 ppm) can cause mass death of brown planthoppers.
[0013] The present invention also found that the LOC_Os03g58380 gene is related to the biosynthesis of homovanillic acid in plants. After knocking out the gene, the homovanillic acid content in rice decreases, and the mortality rate of brown planthoppers when feeding on rice plants in which the gene is knocked out is significantly reduced. Combined with the analysis of the fact that the mortality rate of brown planthoppers when feeding on wild-type rice leaves is significantly higher than that when feeding on rice stems, it is shown that homovanillic acid in rice can affect the survival of brown planthoppers, and high content of homovanillic acid can be used to prevent and control rice pests brown planthoppers.
[0014] Therefore, the present invention claims the following solutions:
[0015] Application of homovanillic acid in controlling brown planthopper.
[0016] Application of homovanillic acid in the preparation of products for controlling brown planthoppers.
[0017] Application of homovanillic acid in controlling plant diseases caused by brown planthopper.
[0018] Application of homovanillic acid in the preparation of products for preventing and controlling plant diseases caused by brown planthopper.
[0019] The application of LOC_Os03g58380 gene in regulating the high vanillic acid content in rice, wherein the nucleotide sequence of the LOC_Os03g58380 gene is a nucleotide sequence encoding the amino acid sequence shown in SEQ ID NO.3.
[0020] As an alternative embodiment, the nucleotide sequence of the LOC_Os03g58380 gene is shown in SEQ ID NO.1.
[0021] As an alternative embodiment, the cDNA sequence of the LOC_Os03g58380 gene is shown as SEQ ID NO.2.
[0022] As an optional embodiment, the application of regulating the high vanillic acid content in rice includes (1) and (2):
[0023] (1) increasing the content of high vanillic acid in rice by increasing the expression of the above gene (LOC_Os03g58380) in plants;
[0024] (2) By inhibiting the expression of the above gene (LOC_Os03g58380) in plants, the high vanillic acid content in rice is reduced.
[0025] Application of the above gene (LOC_Os03g58380 gene) in regulating rice resistance to brown planthopper.
[0026] As an optional embodiment, the use in regulating plant resistance to brown planthoppers includes (1) and (2):
[0027] (1) Improving rice resistance to brown planthoppers by increasing the expression of the above gene (LOC_Os03g58380) in plants;
[0028] (2) By inhibiting the expression of the above gene (LOC_Os03g58380) in plants, the resistance of rice to brown planthoppers is reduced.
[0029] As an optional embodiment, the method for inhibiting the expression of the above-mentioned gene (LOC_Os03g58380) in plants includes: inhibiting the expression of LOC_Os03g58380 gene by RNAi, or knocking out the LOC_Os03g58380 gene in plants by gene editing technology.
[0030] Application of the above gene (LOC_Os03g58380 gene) in reducing the high vanillic acid content in rice
[0031] The application of the above gene (LOC_Os03g58380 gene) in preparing a product for reducing the high vanillic acid content in rice.
[0032] The application of the above gene (LOC_Os03g58380 gene) in screening low-content high-vanillic acid rice varieties.
[0033] The application of the above gene (LOC_Os03g58380 gene) in constructing rice with low resistance to brown planthopper.
[0034] The application of the above gene (LOC_Os03g58380 gene) in reducing the resistance of rice to brown planthopper.
[0035] The use of the above gene (LOC_Os03g58380 gene) in the preparation of products for reducing rice brown planthopper resistance, the preparation of products for reducing rice brown planthopper resistance, and the construction of rice with low resistance to brown planthoppers can be used to prepare plant models resistant to brown planthoppers for use in scientific research.
[0036] The invention provides a method for screening rice varieties resistant to brown planthoppers, comprising the steps of detecting the content of homovanillic acid in rice leaves, stems and leaf sheaths; if the content of homovanillic acid in the leaves, stems and leaf sheaths is not less than 15 μg / g, the rice varieties are determined to be resistant to brown planthoppers; if the content of homovanillic acid in the leaves, stems and leaf sheaths is less than 5 μg / g, the rice varieties are determined to be non-resistant to brown planthoppers.
[0037] The invention provides a method for preventing and controlling brown planthoppers, which comprises treating plants with a product containing homovanillic acid.
[0038] The present invention has the following beneficial effects:
[0039] 1. The present invention has found that homovanillic acid, a secondary metabolite of rice, can be used as a screening index for rice varieties resistant to brown planthoppers. Plants with homovanillic acid content exceeding 15 μg / g in rice leaves, stems and leaf sheaths are used as rice varieties resistant to brown planthoppers, and high content of homovanillic acid in rice leaves, stems and leaf sheaths is used to kill brown planthoppers, thereby achieving the purpose of preventing and controlling rice pests, brown planthoppers. Screening rice with high homovanillic acid content can improve rice resistance to brown planthoppers, providing ideas and technical support for the breeding of rice varieties resistant to brown planthoppers.
[0040] 2. The present invention has found that the mortality rate of brown planthoppers increases significantly after feeding on artificial feed containing homovanillic acid. Therefore, homovanillic acid has a good application prospect and value in the prevention and treatment of brown planthoppers. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Figure 1 Figure 4 shows the mortality of brown planthoppers when feeding on different tissues of rice (Figure a shows the mortality of long-winged adults of brown planthoppers when feeding on different tissues of Zhonghua No. 11 rice; Figure b shows the mortality of 5th instar nymphs of brown planthoppers when feeding on different tissues of Wuxiangsi Miao rice; Figure c shows the mortality of 3rd instar nymphs of brown planthoppers when feeding on different tissues of Nipponbare rice; Figure d shows the mortality of 5th instar nymphs of brown planthoppers when feeding on different tissues of Luyoumingzhan rice; different letters on the bars in the figures indicate significant differences at the P=0.05 level).
[0042] Figure 2The HPLC test results of high vanillic acid content in different tissues of rice (different letters on the bar graph in the figure indicate significant differences at the P=0.05 level).
[0043] Figure 3 Figure 2 shows the mortality of brown planthoppers after feeding on artificial diets supplemented with different concentrations of homovanillic acid (Figure a shows the mortality of 3rd instar nymphs of brown planthoppers after feeding on artificial diets supplemented with different concentrations of homovanillic acid; Figure b shows the mortality of 5th instar nymphs of brown planthoppers after feeding on artificial diets supplemented with different concentrations of homovanillic acid; Figure c shows the mortality of long-winged adults of brown planthoppers after feeding on artificial diets supplemented with different concentrations of homovanillic acid; different letters on the bars in the figures indicate significant differences at the P=0.05 level).
[0044] Figure 4 The mortality rates of brown planthoppers when feeding on wild-type rice and target gene knockout rice (Figure a shows the mortality rates of 3rd instar nymphs of brown planthoppers when feeding on wild-type rice and target gene knockout rice; Figure b shows the mortality rates of 5th instar nymphs of brown planthoppers when feeding on wild-type rice and target gene knockout rice; different letters on the bars in the figures indicate significant differences at the P=0.05 level). DETAILED DESCRIPTION
[0045] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.
[0046] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.
[0047] Homovanillic acid, CAS number: 306-08-1, structural formula:
[0048] The artificial feed in Example 3 contains amino acids, vitamins, inorganic salts and sucrose. The specific formula is referred to the literature "Fu Q, Zhang Z, Hu C, Lai F, Sun Z, 2001. A chemically defined diet enables continuous rearing of the brown planthopper Nilaparvata lugens (Homoptera: Delphacidae). Appl. Entomol. Zool., 36(1): 111-116.》MMD-1 formula.
[0049] The knockout of the aldehyde oxidase gene (LOC_Os03g58380) in Example 4 was commissioned to BioGene Technology Co., Ltd.
[0050] Example 1 Bioassay of brown planthopper feeding on different rice tissues
[0051] 1. Experimental Methods
[0052] The rice varieties used in this experiment are japonica rice (Zhonghua No. 11 and Nihonbare) and indica rice (Luyoumingzhan and Wuxiangsi Miao). The 3rd and 5th instar nymphs and long-winged adults of brown planthoppers were placed in large insect bags, which were covered on the whole rice plant so that the pests could feed freely on the rice. The 3rd and 5th instar nymphs and long-winged adults of brown planthoppers were placed in small insect bags, which were covered on the leaves, sheaths or stems of rice so that the pests could only feed on the leaves, sheaths or stems of rice in the insect bags. The mortality of brown planthoppers in different insect bags was observed every day.
[0053] 2. Experimental Results
[0054] Under indoor conditions, the mortality of 3rd and 5th instar nymphs and long-winged adults on the 3rd and 7th days after feeding on different parts of rice tissues is as follows: Figure 1 The results showed that: in the 7-day test, compared with feeding only on rice stems, the mortality of 3rd instar nymphs of brown planthoppers increased by 20% to 55%, the mortality of 5th instar nymphs increased by 15% to 60%, and the mortality of long-winged adults increased by 13% to 50% when feeding only on rice leaves; the mortality of 3rd instar nymphs of brown planthoppers increased by 5% to 25%, the mortality of 5th instar nymphs increased by 5% to 30%, and the mortality of long-winged adults increased by 3% to 15% when feeding only on rice sheaths. Among them, when brown planthoppers fed on rice Luyoumingzhan, compared with feeding only on stems, when brown planthoppers only fed on Luyoumingzhan leaves, the mortality of 3rd instar nymphs increased by 48.4% on the 7th day, the mortality of 5th instar nymphs increased by 47.2% on the 7th day, and the mortality of long-winged adults increased by 40% on the 7th day.
[0055] Example 2 Determination of the content of high vanillic acid in different tissues of rice
[0056] 1. Experimental methods
[0057] (1) Preparation of standard curve
[0058] Weigh an appropriate amount of homovanillic acid sample and add it to the solvent (a mixture of methanol and potassium dihydrogen phosphate, V:V = 25:75) to prepare homovanillic acid solutions with concentrations of 0.5, 1.5, 4.5, 13.5, 40.5, and 121.5 ppm. First, take 20 μL of solvent for sample loading to obtain the peak area of the solvent, and then take 20 μL of the prepared solution for sample loading to obtain the peak area of the sample solution. The peak area of the homovanillic acid sample is the peak area of the sample solution minus the peak area of the solvent. The concentration of homovanillic acid and its peak area are used for linear regression analysis to obtain the standard curve of the standard sample. HPLC detection conditions: DAD detector. C18 chromatographic column: 250*4.6mm; 5μm. Column temperature 25℃, flow rate: 1mL / min. Injection volume: 20μL. Wavelength: 280nm. Mobile phase: methanol: potassium dihydrogen phosphate (0.01mol / L) = 25:75 elution.
[0059] (2) Determination of vanillic acid content in rice leaves, sheaths and stems
[0060] The rice varieties used in this experiment are japonica rice (Zhonghua No. 11 and Nihonbare), indica rice (Luyoumingzhan and Wuxiangsimiao), etc. The leaves, sheaths and stems of rice were ground into powder with liquid nitrogen, a certain amount (3g) of sample was weighed into a centrifuge tube, an appropriate amount of methanol (30mL) was added, and the sample was placed in an oscillator for full oscillation and mixing for 1-2min, then centrifuged at 4000r / min for 10min, the supernatant was transferred to a new centrifuge tube, the above operation was repeated several times, the supernatant was combined and mixed, dried with nitrogen at room temperature, the supernatant was taken after dissolving an appropriate amount of methanol, and passed through a 0.22μm filter membrane, and 20μL of sample was taken for liquid chromatography detection.
[0061] 2. Experimental results
[0062] We conducted HPLC detection on tissues of different parts of rice varieties such as Luyoumingzhan, Wuxiangsimiao, Zhonghua No. 11 and Nipponbare, and found that homovanillic acid is commonly present in tissues of rice stems, leaf sheaths, leaves and other parts, with a content ranging from 0.2μg / g to 45μg / g. Among them, the content of homovanillic acid in leaves is relatively high, ranging from 14μg / g to 45μg / g, and the content of homovanillic acid in stems and leaf sheaths is relatively low, ranging from 0.2μg / g to 10μg / g.
[0063] Among them, taking the experimental results of rice Luyoumingzhan as an example, the HPLC test results of the high vanillic acid content in the tissues of different parts of rice Luyoumingzhan are shown in Figure 2 The results showed that the content of homovanillic acid in the leaves, sheaths and stems of Luyoumingzhan was quite different, with the highest content in the leaves being 17.4μg / g; the second highest content in the sheaths being 4.2μg / g; and the lowest content in the stems being 0.9μg / g.
[0064] The resistance of different rice varieties to brown planthoppers was compared and graded based on the content of homovanillic acid in the stems, leaf sheaths and leaf tissues of rice. A large amount of data analysis results showed that the resistance of different rice varieties to brown planthoppers can be identified and differentiated based on the content of homovanillic acid in rice leaves, stems and leaf sheaths. The specific standards are: if the content of homovanillic acid in leaves, stems and leaf sheaths is not less than 15μg / g, the rice variety is judged to be resistant to brown planthoppers; if the content of homovanillic acid in leaves, stems and leaf sheaths is less than 5μg / g, the rice variety is judged to be non-resistant to brown planthoppers.
[0065] Example 3 Toxicity determination of homovanillic acid to brown planthopper
[0066] 1. Experimental methods
[0067] The 3rd and 5th instar nymphs and long-winged adults of brown planthoppers were taken and placed in insect bottles (350 ml mineral water bottles, with 40 mesh gauze glued to the bottom after removing the bottle), and the bottle mouth was covered with a double-layer parafilm sealing film. Artificial feed could be added in the middle of the sealing film for brown planthoppers to eat. The mortality of brown planthoppers was observed every day.
[0068] 2. Experimental results
[0069] After brown planthoppers fed on artificial diets containing 0.5-30 ppm homovanillic acid, the mortality of 3rd and 5th instar nymphs and long-winged adults of brown planthoppers on the 7th day increased by 2.5%-260% compared with the control group (added with 0 ppm homovanillic acid).
[0070] When the artificial diet contained 0, 0.9, and 17 ppm of homovanillic acid (i.e., the final concentration of homovanillic acid in the artificial diet was 0, 0.9, and 17 ppm, respectively), the mortality rates of the 3rd and 5th instar nymphs and long-winged adults of brown planthoppers on the 3rd and 7th days after feeding on the artificial diet containing different concentrations of homovanillic acid were as follows: Figure 3 The results show that when the 3rd and 5th instar nymphs and long-winged adults of brown planthoppers fed on artificial diets containing 0.9 ppm homovanillic acid (the same content as in rice stems), the mortality rates on the 7th day increased by 2.6%, 21.5% and 3.6% compared with those of the control group; when they fed on artificial diets containing 17 ppm homovanillic acid (the same content as in rice leaves), the mortality rates on the 7th day increased by 27.9%, 242.5% and 39.4% compared with those of the control group. This indicates that homovanillic acid, a secondary metabolite of rice, can cause massive mortality of brown planthoppers at high concentrations.
[0071] Example 4 Knocking out the aldehyde oxidase gene can reduce the content of high vanillic acid in plants and reduce the toxicity of plants to brown planthoppers
[0072] 1. Experimental Methods
[0073] (1) Using the rice variety Zhonghua 11 as the background, the aldehyde oxidase gene (LOC_Os03g58380) in rice was knocked out to obtain the aldehyde oxidase gene knockout plants, and the homovanillic acid content in different tissues (leaves, leaf sheaths, and stems) of the knockout plants was detected, and the detection method was the same as that in Example 2.
[0074] (2) Take the 3rd and 5th instar nymphs of brown planthoppers and place them in small insect bags. The small insect bags are placed on the leaves or stems of rice so that the pests can only feed on the leaves or stems of rice in the insect bags. The mortality of brown planthoppers in different insect bags is observed every day.
[0075] The nucleotide sequence of the LOC_Os03g58380 gene (aldehyde oxidase gene) is shown in SEQ ID NO.1:
[0076] .
[0077] The cDNA sequence of LOC_Os03g58380 gene (aldehyde oxidase gene) is shown in SEQ ID NO.2:
[0078] ATGAACGATGGCTCCATCGCCGGCGGCTTCGAGATCGGTCAGGGGCTATGGACAAAGGTGAAGCAGATGACCGCGTTCGCGCTGGGCCAGTTGTGCGATGATCTCGACAAGGTCCATGTCATCCTC ATCCAGGCTGACACACTGAGCATGATCCATCAAGGAGAAGGCTGGTACCCTACCATGGAAATCCTTGATTGCCCAGGCAAGCATGGCGAGTGTGAAGCTGACGGAGCATACGTACTGGACCCCTGA.
[0079] The amino acid sequence of the LOC_Os03g58380 gene (aldehyde oxidase gene) is shown in SEQ ID NO.3:
[0080] MNDGSIAGGFEIGQGLWTKVKQMTAFALGQLCDDLDKVHVILIQADTLSMIHQGEGWYPTMEILDCPGKHGECEADGAYVLDP*.
[0081] 2. Experimental Results
[0082] (1) HPLC detection was performed on the leaves, sheaths and stems of the aldehyde oxidase gene knockout plants. The test results are shown in Table 1. The results showed that compared with the wild-type plants, the content of homovanillic acid in the leaves, sheaths and stems of rice after the aldehyde oxidase gene was knocked out decreased by 12% to 82%. This indicates that the aldehyde oxidase gene in rice is related to the biosynthesis of homovanillic acid, a secondary metabolite of rice.
[0083] Table 1 Contents of homovanillic acid in leaves of wild-type and knockout plants
[0084] Zhonghua 11 wild type Target gene knockout mutant High vanillic acid content (μg / g) 1.74±0.25 0.65±0.17
[0085] (2) The mortality rates of the 3rd and 5th instar nymphs of brown planthopper when they only fed on wild-type rice and target gene knockout rice, respectively. Figure 4 shown.
[0086] Compared with feeding only on wild-type rice leaves, the mortality rate of third-instar nymphs of brown planthoppers fed only on leaves of knockout mutant rice of the aldehyde oxidase gene was reduced by 60% to 80%, and the mortality rate of fifth-instar nymphs was reduced by 50% to 85%.
[0087] In summary, the mortality rate of 3rd and 5th instar nymphs of brown planthoppers when feeding only on rice leaves can be increased by 80% compared with the mortality rate when feeding only on stems. The reason is that the content of homovanillic acid in rice leaves (greater than 15 μg / g) is higher (more than 650%) than that in stems (less than 2 μg / g). The experimental data after adding different concentrations of homovanillic acid to artificial feed further shows that high concentrations of homovanillic acid can greatly increase the mortality rate of brown planthoppers. Therefore, homovanillic acid in rice can be used to control brown planthoppers, and screening rice varieties with high homovanillic acid content can be used to breed rice resistant to brown planthoppers.
[0088] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.
Claims
1. Application of homovanillic acid in controlling brown planthopper.
2. Application of homovanillic acid in the preparation of products for controlling brown planthoppers.
3. Application of homovanillic acid in preventing and controlling plant diseases caused by brown planthopper.
4. Application of homovanillic acid in the preparation of products for preventing and controlling plant diseases caused by brown planthoppers.
5. Application of the LOC_Os03g58380 gene in regulating the high vanillic acid content in rice, characterized in that: The nucleotide sequence of the LOC_Os03g58380 gene is a nucleotide sequence encoding the amino acid sequence shown in SEQ ID NO.
3.
6. Use of the gene according to claim 5 in regulating rice resistance to brown planthopper.
7. Use of the gene according to claim 5 in reducing the high vanillic acid content in rice, or in preparing a product with reduced high vanillic acid content in rice, or in screening low-content high vanillic acid rice varieties.
8. Use of the gene of claim 5 in constructing rice with low resistance to brown planthoppers, or in reducing the resistance of rice to brown planthoppers, or in preparing a product for reducing the resistance of rice to brown planthoppers.
9. A method for screening rice varieties resistant to brown planthoppers, characterized in that: The content of homovanillic acid in rice leaves, stems and leaf sheaths is tested; if the content of homovanillic acid in the leaves, stems and leaf sheaths is not less than 15μg / g, the rice is judged to be a rice variety resistant to brown planthoppers; if the content of homovanillic acid in the leaves, stems and leaf sheaths is less than 5μg / g, the rice is judged to be a non-brown planthopper resistant rice variety.
10. A method for controlling brown planthopper, characterized in that: Treat the plants with a product containing homovanillic acid.