Application of sakurain in controlling rice false smut

Abstract

The present invention discloses the application of sakurain in preventing and controlling rice false smut. The present invention discloses the function of sakurain, a flavonoid compound, as a fungicide in preventing and controlling rice false smut. Experiments have shown that sakurain can inhibit the mycelial growth and spore germination of rice false smut fungi. 50 The concentration of sakurain was 10 μg / mL, indicating that sakurain has strong inhibitory activity against the pathogenicity of rice smut fungus. Therefore, this study lays the foundation for the use of sakurain as a fungicide to control rice smut and provides new ideas for the development of innovative pollution-free botanical pesticides.

Description

Technical Field

[0001] The invention relates to research on application of a flavonoid compound sakurain as a fungicide in treating rice false smut, and belongs to the technical field of biological pesticides. Background Art

[0002] Rice is the main source of food for about 3 billion people in the world. In recent years, rice diseases have become increasingly serious. As of 2021, the area of ​​rice false smut (Ustilaginoidea virens) caused by the green sclerotinia of rice accounted for 11.6% of the rice disease area in my country. It has jumped from a minor rice disease to one of the three major rice diseases in my country, attracting widespread attention. This disease not only causes serious yield losses or even total failure, but also seriously threatens people's health by producing toxins. At present, the most effective method for preventing and controlling rice false smut is the application of fungicides, but excessive reliance on the above fungicides will lead to a series of problems such as pathogen resistance, fungicide residues, and ecological environmental damage. Therefore, finding a highly efficient, pollution-free, non-resistant, green and healthy fungicide has become the main research content for the prevention and control of rice false smut.

[0003] Studies have shown that flavonoids are a type of secondary metabolite widely distributed in plants, have a wide range of antibacterial activity, can be used as fungicides, and have become a new research direction for the prevention and control of rice false smut. Sakurain is one of the most representative plant natural products among all flavonoids. Sakurain is a flavanone compound in which the 7th hydroxyl group of naringenin is replaced by a methoxy group. In 1989, Kodama first isolated it from rice leaves infected with rice blast (Piricularia oryzae) and found that sakurain has inhibitory activity on the spore germination and hyphae growth of the fungus Pyricularia oryzae. The EC of sakurain on the germination of rice blast spores was 2.34, which was higher than that of naringenin. 50 =15μg / mL, EC for the growth of rice blast fungus 50 =5μg / mL. In 2014, Park et al. found that sakuramin has a strong inhibitory activity on the germ tube growth of rice blast fungus. 50 5μg / mL, which is more effective than diterpenoid phytoalexins; sakurain inhibits the mycelial growth of rice blast fungus, IC 50 The concentration of sakurain in rice was 6.44 μg / mL. Sakurain also inhibited the growth of Bacillus oryzae and the mycelium of Rhizoctonia solani (the rice sheath blight fungus). In 2021, Zhongyan Yang discovered that sakurain also has an anti-brown planthopper effect on rice. However, no reports have been found on the inhibitory effect of sakurain on rice smut pathogens.

[0004] Rice blast can infect rice seedlings, leaves, panicles, and internodes throughout the entire growing season. The pathogen is a member of the Deuteromycetes family, Pyricularia oryzae (Cav.), a genus of the Deuteromycetes; the sexual stage is Magnaporthe grisea (Barr.), a genus of the Ascomycetes. Rice false smut is fundamentally different, primarily affecting the panicle during the booting stage. It belongs to the Deuteromycetes. The sexual stage is Claviceps virens Sakurai, a member of the Ascomycetes. Hosts include rice, corn, wild rice, and millet (Digitaria spp.). The incidence rate ranges from 3% to 5%, with severe cases exceeding 30%, resulting in yield reductions of 20% to 30%. The relationship between U.S. smut and the blast pathogen is quite distant in species. In terms of evolutionary relationship, U.S. smut is closer to Metarhizium anisopliae and more distant to the blast pathogen.

[0005] Although reports have shown that sakurain can inhibit the growth of mycelia and spore germination of the rice blast fungus, its inhibitory effect on the mycelia and spores of the rice blast pathogen remains unknown. For example, triadimefon is a highly systemic fungicide with bidirectional transmission, which can inhibit the normal development of the pathogen's appressorium and haustoria in plants, hindering mycelial growth and spore formation. However, it has no effect on oomycetes because their mycelia lack septa, making them uninhibited. Comparative genomics results show that compared with other pathogens such as rice blast, the rice blast pathogen has significantly fewer genes involved in redox reactions, related to toxins, and proteins involved in stimulating metabolism. This indicates that the genomic composition of the rice blast pathogen and the rice blast pathogen are significantly different, and the species are relatively distant in evolutionary relationship. Therefore, it is difficult to predict whether sakurain will be effective against the rice blast pathogen. Summary of the Invention

[0006] The purpose of the present invention is to provide application of sakurain in preventing and treating rice false smut.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] Application of sakurain in controlling rice false smut.

[0009] As a preferred embodiment of the present invention, sakuramin is used to inhibit the mycelial growth and / or spore germination of rice false smut fungus.

[0010] Application of sakurain in the preparation of biological pesticides for controlling rice false smut.

[0011] Application of sakurain in inhibiting the pathogen of rice false smut.

[0012] Application of sakurain in the preparation of biological pesticides for inhibiting the pathogen of rice false smut.

[0013] The sakurain used in the present invention was purchased from Merck (cas: 2957-21-3) and dissolved in dimethyl sulfoxide (DMSO).

[0014] In the sakurain solution used as the pharmaceutical agent of the present invention, the concentration of sakurain is in the range of 0.5-20 μg / mL.

[0015] Beneficial effects of the present invention: The present invention discloses the function of flavonoid compound sakurain as a fungicide in preventing and treating rice false smut. Experiments have shown that sakurain can inhibit the mycelial growth and spore germination of rice false smut fungus. 50 The concentration of sakurain was 10 μg / mL, indicating that sakurain has strong inhibitory activity against the pathogenicity of rice smut fungus. Therefore, this study lays the foundation for the use of sakurain as a fungicide to control rice smut and provides new ideas for the development of innovative pollution-free botanical pesticides. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the inhibition of different concentrations of sakurain on the mycelial growth of rice false smut fungus.

[0017] Figure 2 The results show that the inhibition rates of sakurain at different concentrations on the mycelial growth of rice smut pathogen were 24%, 37%, 48%, 60%, and 71% at concentrations of 0.5μg / mL, 5μg / mL, 10μg / mL, 15μg / mL, and 20μg / mL, respectively, indicating that sakurain has good anti-rice smut pathogen activity. The regression equation is y=0.0239x+0.2391, R 2 =0.9977. IC 50 =10μg / mL, indicating that sakurain has a strong ability to resist rice blast fungus.

[0018] Figure 3 It is sakurain that inhibits the germination of rice false spores. DETAILED DESCRIPTION

[0019] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0020] Example 1

[0021] 1. Experimental method: The mycelium inhibition rate method was used to study the inhibitory effect of sakura extract on the mycelial growth of U. oryzae var. oryzae.

[0022] 2. The specific methods are as follows:

[0023] In a laminar flow hood, evenly spread the U.S. smut pathogen HWD-2, stored at -80°C, onto PSA medium and incubate inverted in the dark at 28°C for 14 days. Use a 5mm sterile borer to transfer the U.S. smut pathogen to fresh PSA medium and continue incubating for another 14 days until mycelium has grown to two-thirds of the medium, ready for inoculation.

[0024] Sakura extract was dissolved in dimethyl sulfoxide (DMSO) to prepare a higher concentration stock solution for later use. In a clean bench, 20 mL of PSA medium was poured into a 50 mL sterile centrifuge tube. Then, different concentrations of the stock solution were added to prepare drug-containing medium with final concentrations of 0.5 μg / mL, 5 μg / mL, 10 μg / mL, 15 μg / mL, and 30 μg / mL. The medium was mixed, poured onto plates, and air-dried. The control group was PSA medium containing the corresponding DMSO concentration. Three replicates were set for each treatment.

[0025] In the clean bench, first sterilize the puncher (5mm), tweezers and other tools at high temperature. When the puncher cools down to room temperature, select the edge of the mycelium of the rice smut pathogen and make vertical holes. Use sterile tweezers to invert the bacterial cake (the mycelium is close to the surface of the drug-containing culture medium) and place it in the center of the PSA culture medium. Incubate in a 28°C constant temperature light incubator and culture in the dark for 14 days. When the mycelium of the control group grows to about two-thirds of the culture medium, use the cross-cross method to measure the mycelium diameter and calculate the inhibition rate of sakura extract on the rice smut pathogen. The calculation formula is:

[0026] Inhibition rate (%) = (colony diameter of control group - colony diameter of treated group) ÷ (colony diameter of control group - punch diameter).

[0027] Through experiments on mycelial growth of the rice smut pathogen, the present invention found that sakurain can inhibit mycelial growth and spore germination of the pathogen, demonstrating strong anti-smut activity. At concentrations of 0.5 μg / mL, 5 μg / mL, 10 μg / mL, 15 μg / mL, and 20 μg / mL, sakurain showed inhibition rates of 24%, 37%, 48%, 60%, and 71% against mycelial growth of the pathogen, respectively.

[0028] Example 2

[0029] 1. Experimental method: The present invention studies the inhibitory effect of sakura chlorophyll on the spore germination of rice false smut fungus.

[0030] 2. The specific methods are as follows:

[0031] After activating HWD-2, a strain of rice smut fungus, on PSA solid medium for approximately 14 days, several mycelial fragments were excised and transferred to PSB liquid medium. The mixture was shaken at 28°C and 200 rpm for 5-7 days to obtain a large amount of mycelial and spore mixture. The mycelial and spore mixture was filtered through sterile gauze and used as seed medium. On a coverslip, a PSA medium containing sakura sakura extract at concentrations of 5 μg / mL and 14 μg / mL was prepared. The seed medium was evenly spread on the solid medium, air-dried, and the coverslip placed in a Petri dish in an incubator at 28°C. A filter paper sheet was placed in the Petri dish and moistened with sterile water to provide suitable humidity for spore germination. Spore germination was observed under a microscope at 8, 12, and 24 hours.

[0032] Summary of experimental results: Through the rice false spore germination test, the present invention found that at concentrations of 5μg / mL and 14μg / mL, the spore germination rates after treatment for 8 hours were 1.6% and 0.3%, respectively, indicating that sakurain has strong biological activity against rice false spore pathogens.

[0033] 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 considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. Application of sakurain in preventing and controlling rice false smut.

2. The use according to claim 1, characterized in that Application of sakurain in inhibiting mycelial growth and / or spore germination of rice false smut fungus.

3. Application of sakurain in the preparation of biological pesticides for preventing and controlling rice false smut.

4. Application of sakurain in inhibiting rice false smut pathogen.

5. Application of sakurain in the preparation of biological pesticides for inhibiting rice false smut pathogens.

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