Application of an inducer in controlling rice planthoppers

Abstract

The present invention relates to the technical field of agricultural pest control, and more particularly to the use of an inducer for controlling rice planthoppers. The present invention utilizes 1-oxo-indanyl-L-isoleucine methyl ester in rice to improve the rice's resistance to planthoppers while maintaining its growth and agronomic characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural pest control, in particular to application of an inducer in controlling rice planthoppers. Background Art

[0002] Rice (Oryza sativa L.) is one of the world's major food crops, feeding more than half of the world's population. During the rice cultivation process, it is threatened by a variety of pests, and the rice planthopper (Nilaparvata lugens Brown planthopper (BPH) is one of the major pests in rice fields. It belongs to the family Delphacidae in the order Hemiptera. It survives by sucking sap from rice stems and leaves. It also affects rice yield and quality by laying eggs, spreading or inducing rice diseases, and seriously threatens global food security.

[0003] Currently, the primary method for controlling rice planthoppers is chemical control, such as pesticides. However, the long-term and extensive use of chemical pesticides has led to the development of resistance in rice planthoppers, which in turn has led to increased pesticide usage and frequency, significantly increasing the cost of control. Furthermore, the extensive use of chemical pesticides can lead to pesticide residues, which can negatively impact the environment, non-target organisms, and humans and livestock. Therefore, exploring greener and more environmentally friendly methods for controlling rice planthoppers is crucial for addressing global food security.

[0004] Plant elicitors are a class of small molecule compounds, peptides or proteins that can activate plant resistance to diseases and insects. Most of the currently known elicitors are targeted at plant pathogens, while research on elicitors related to insect resistance is very limited. The jasmonic acid (JA) hormone signaling pathway plays a core role in plant resistance to insects. On the one hand, JA can activate the expression of insect-resistant related genes and the synthesis of insect-resistant substances in plants, thereby improving the insect resistance of plants; on the other hand, JA will inhibit plant growth. The dual effects on plants have severely limited the application of JA as an elicitor in agricultural production. In recent years, studies have reported chemical modifications of JA and its derivatives to activate plant defenses without affecting plant growth. However, most of the existing research focuses on the model plant Arabidopsis thaliana, and there is little research on crop resistance to insects. Summary of the Invention

[0005] The purpose of the present invention is to provide the application of 1-oxoindane-4-carboxylicacid and methyl isoleucine methyl ester in the prevention and control of rice planthoppers. Jasmonic acid-isoleucine (JA-Ile) is a biologically active JA molecule in vascular plants. It is an amino acid conjugate that plays an important role in plant stress defense and development. In the early experiments of the present invention, its molecular structure was chemically modified to synthesize a conjugate of indanyl and isoleucine, named In-Ile (1-oxoindane-4-carboxylicacid and methyl isoleucine conjugate). Further studies found that In-Ile can improve the resistance of rice to rice planthoppers without affecting the growth of rice, whether in the greenhouse or in the field.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides an application of an inducer in controlling rice planthoppers, wherein the inducer is 1-oxo-indanyl-L-isoleucine methyl ester. The structural formula of the compound is as follows: Figure 5 shown.

[0008] Preferably, 1-oxo-indanyl-L-isoleucine methyl ester is applied to rice plants to induce a defense response in the rice.

[0009] Preferably, the concentration of 1-oxo-indanyl-L-isoleucine methyl ester is 20 μM to 5 mM.

[0010] The present invention also provides a medicine for preventing and controlling rice planthoppers, comprising 1-oxo-indanyl-L-isoleucine methyl ester and auxiliary materials.

[0011] Preferably, the final concentration of the 1-oxo-indanyl-L-isoleucine methyl ester in the drug is 20 μM to 5 mM.

[0012] Preferably, the auxiliary material is lanolin or anhydrous ethanol.

[0013] The preferred formulation of the drug is an aqueous solution or an oily solution.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The present invention applies 1-oxo-indanyl-L-isoleucine methyl ester to the control of rice planthoppers, which not only improves the resistance of rice to rice planthoppers, but also does not affect the growth and agronomic traits of rice. The synthesis pathway of the compound is relatively simple, and it is an analog of plant hormones. It is an environmentally friendly compound with great potential for field application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0017] Figure 1 This is the effect of In-Ile treatment on rice growth.

[0018] Figure 2 This is the effect of In-Ile treatment on rice resistance.

[0019] Figure 3 Effects of In-Ile-treated rice on feeding by rice planthoppers.

[0020] Figure 4 This is the effect of In-Ile treatment on the resistance of field rice to planthoppers and the effect of In-Ile treatment on the agronomic traits of field rice.

[0021] Figure 5 The structural formula is In-Ile. DETAILED DESCRIPTION

[0022] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0023] Example 1 Greenhouse experiment to evaluate changes in rice growth after In-Ile treatment

[0024] 1. Rice seeds (Xiushui 11) were evenly sown in a water-containing culture dish and placed in a light incubator (28 ± 1°C, photoperiod of 14 h L:10 h D) for germination. The seeds were washed every 12 h, and the seed surface was kept moist but not soaked. After 7 days, the seedlings were transferred to a greenhouse (temperature 28 ± 2°C, photoperiod of 14 h L:10 h D, humidity 50%) and cultured in rice culture medium with regular replacement of the culture medium. After 17 days of culture, the seedlings were used in experiments.

[0025] 2. Before the experiment, rice plants with good and consistent growth were selected and planted individually in opaque plastic cups (8 cm in diameter, 10 cm in height) containing culture solution (formula provided in Table 1, the same below) and allowed to recover for 3 days.

[0026] 3. In-Ile was administered via root uptake. First, In-Ile was dissolved in anhydrous ethanol to a 400 mM stock solution, which was then dissolved in freshly prepared nutrient solution to ensure a final In-Ile concentration of 20 μM. An equal amount of anhydrous ethanol was added to the control group. Rice plants were placed in the nutrient solution for both the treatment and control groups, with the roots submerged. After three days of root uptake, the nutrient solution for both groups was replaced with freshly prepared nutrient solution. Plant height, leaf sheath height, root tissue fresh weight, and total plant fresh weight were recorded on day 23 after treatment.

[0027] The data were statistically analyzed using DPS software, and comparisons between two samples were performed using the Student's t-test. Asterisks in the figures indicate significant differences between groups (*, p < 0.05; **, p < 0.01; Student's t-test); ns indicates no significant difference between groups.

[0028] Table 1 Nutrient solution composition

[0029] Components Content mg / L <![CDATA[CaCl2]]> 110.75 <![CDATA[NaH2PO4·H2O]]> 50.375 <![CDATA[MgSO4·2H2O]]> 405 <![CDATA[MnCl2·4H2O]]> 1.875 <![CDATA[H3BO3]]> 1.168 <![CDATA[CuSO4·5H2O]]> 0.039 <![CDATA[(NH4)6Mo7O 24 ·4H2O]]> 0.093 <![CDATA[ZnSO4·7H2O]]> 0.044 <![CDATA[FeCl3·6H2O]]> 9.625 Citric acid monohydrate 14.875 <![CDATA[H2SO4]]> 0.049mL / L <![CDATA[KNO3]]> 103.525 <![CDATA[(NH4)2SO4]]> 94.46

[0030] Test results

[0031] We evaluated the growth of rice after In-Ile treatment, and the results were as follows Figure 1 The results show that In-Ile treatment of rice showed no significant differences in plant height, leaf sheath length, root fresh weight, or total plant fresh weight compared to the control group. These results indicate that In-Ile treatment of rice does not affect its growth and is safe.

[0032] Example 2: Greenhouse experiment to evaluate the effect of In-Ile treatment on rice pest tolerance

[0033] 1. This experiment uses the mortality rate of rice leaves damaged by egg-bearing female adults of rice planthoppers as a measurement indicator to evaluate rice resistance to rice planthoppers.

[0034] 2. Rice seeds were evenly sown in a Petri dish containing water and placed in a light incubator (28±1°C, photoperiod of 14 h L:10 h D) for germination. The seeds were washed every 12 h, and the seed surface was kept moist but not soaked. After 7 days, the seedlings were transferred to a greenhouse (temperature 28±2°C, photoperiod of 14 h L:10 h D, humidity 50%) and cultured in rice culture medium, which was replaced regularly. After 17 days of culture, the seedlings were used in experiments.

[0035] 3. Before the experiment, select rice plants with good and consistent growth, plant them individually in a light-proof plastic cup (8 cm in diameter, 10 cm in height) containing culture medium, cover them with a gauze cover that is large enough to cover the entire rice plant, and allow them to recover for 3 days.

[0036] 4. In-Ile was tested by root uptake. First, In-Ile was dissolved in anhydrous ethanol to a 400 mM stock solution. This stock solution was then dissolved in freshly prepared nutrient solution to ensure a final In-Ile concentration of 20 μM. An equal amount of anhydrous ethanol was added to the control group. Rice plants were placed in the nutrient solution for both the treatment and control groups, with the roots submerged. After three days of root uptake, the nutrient solution for both the treatment and control groups was replaced with freshly prepared nutrient solution.

[0037] 5. Inoculate 25 female adult rice planthoppers bearing eggs into each rice plant. Observe the rice plant status every day. If any rice planthoppers die, replenish the population to 25. Remove the gauze cover after 8 days, observe the growth status of the rice, and calculate the death rate of each rice leaf. Take photos and record.

[0038] Test results

[0039] We evaluated the effect of In-Ile treatment on rice resistance to rice planthoppers. Figure 2 The results show that the leaf mortality rate of rice treated with In-Ile after being attacked by rice planthoppers was significantly lower than that of the control group, with a 35% reduction. This result shows that In-Ile treatment improves rice resistance to rice planthoppers.

[0040] Example 3: Greenhouse experiment to evaluate the effect of In-Ile-treated rice on rice planthopper feeding

[0041] 1. This experiment used the honeydew secretion and weight gain of egg-bearing female adults of rice planthoppers on rice plants as measurement indicators to evaluate the resistance of rice to rice planthoppers.

[0042] 2. Rice seeds were evenly sown in a Petri dish containing water and placed in a light incubator (28±1°C, photoperiod of 14 h L:10 h D) for germination. The seeds were washed every 12 h, and the seed surface was kept moist but not soaked. After 7 days, the seedlings were transferred to a greenhouse (temperature 28±2°C, photoperiod of 14 h L:10 h D, humidity 50%) and cultured in rice culture medium with regular nutrient solution changes. After 17 days of culture, the seedlings were used in experiments.

[0043] 3. Before the experiment, well-grown and uniform rice plants were selected and planted individually in light-proof plastic cups (8 cm in diameter and 10 cm in height) containing nutrient solution. Homemade Parafilm sealing film bags were used as a device to collect honeydew. The initial weight of each bag was recorded. The bag was placed on the leaf sheath 10 cm above the rice root and allowed to recover for 3 days.

[0044] 4. In-Ile was tested for root uptake by dissolving In-Ile in anhydrous ethanol to a 400 mM stock solution. This stock solution was then dissolved in freshly prepared nutrient solution to ensure a final In-Ile concentration of 20 μM. An equal amount of anhydrous ethanol was added to the control group. Rice plants were placed in the nutrient solution for the treatment and control groups, submerging the roots. After three days of root uptake, the nutrient solution for both treatment and control groups was replaced with freshly prepared nutrient solution.

[0045] 5. One newly emerged female adult of the rice planthopper was inoculated into each rice plant. Before inoculation, the female adult was captured in a 1.5 mL centrifuge tube and numbered. The weight of the centrifuge tube and the female adult was weighed and recorded on a 1 / 100,000 scale. The centrifuge tube was retained after inoculation. Three days later, the female adult with the same number as the centrifuge tube was removed from the centrifuge tube. The weight of the honeydew pocket after honeydew production was weighed and recorded using the same 1 / 100,000 scale to calculate the honeydew secretion. The weight of the centrifuge tube and the treated female adult of the rice planthopper was also weighed and recorded on a 1 / 100,000 scale to calculate the insect's weight gain.

[0046] Test results

[0047] We evaluated the effect of In-Ile treatment on rice resistance to rice planthoppers. Figure 3 The results show that honeydew secretion and weight gain of rice planthoppers after feeding on In-Ile-treated rice were significantly lower than those in the control group, with honeydew secretion reduced by 44.86% and weight gain reduced by 40.23%. These results indicate that In-Ile treatment inhibits rice planthopper feeding.

[0048] Example 4 Field Trial Evaluation of Agronomic Traits and Resistance to Rice Planthoppers in Rice Treated with In-Ile

[0049] 1. The field experiment was carried out at Xinglong Agricultural Machinery Professional Cooperative, Tonglu County, Hangzhou City, Zhejiang Province (29°79′47″N, 119°67′15″E). Ten blocks were set up in the field plot. An average of 25 rice seedlings were planted in each block. When the rice grew to 15 weeks old, the base of the rice leaf sheaths in 5 of the blocks was smeared with 20 μL of lanolin containing 5 mM In-Ile, while the rice in the other blocks was smeared with 20 μL of lanolin containing an equal amount of anhydrous ethanol. In order to evaluate the performance of rice planthoppers in rice with different treatments, rice planthoppers were collected into white porcelain trays by gently tapping random plants in the blocks 7 days after treatment. In order to evaluate the agronomic traits of rice with different treatments, agronomic traits were measured and photographed 21 days after treatment.

[0050] Test results

[0051] We evaluated the effects of In-Ile treatment on rice planthopper resistance and agronomic traits in field trials. Figure 4 As shown, it shows the application location of lanolin and the growth of rice in the control group and In-Ile group, and its effect on the agronomic traits of rice. The number of rice planthoppers on In-Ile-treated rice was significantly lower than that in the control group, with the number of adults reduced by 60.55% and the number of nymphs reduced by 32.77%. There was no significant difference in plant height, yield per plant, 1000-grain weight, fruit set rate, and number of panicles per plant between the In-Ile-treated rice and the control group. The results showed that In-Ile treatment of rice improved resistance to rice planthoppers without affecting the agronomic traits of rice.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An application of an inducer in controlling rice planthoppers, characterized in that: The inducer is 1-oxo-indanyl-L-isoleucine methyl ester; 1-oxo-indanyl-L-isoleucine methyl ester is applied to rice plants.

2. The use according to claim 1, characterized in that The inducer is used at a concentration of 20 μM to 5 mM.

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