Application of acridine derivative in prevention and treatment of fungal diseases of plants

Abstract

The invention belongs to the technical field of plant disease prevention and treatment, and provides application of acridine derivatives in prevention and treatment of plant fungal diseases. The acridine derivative provided by the invention has obvious inhibitory activity on main pathogenic fungi of tobacco and rice, and the acridine derivative has a synergistic effect when compounded with fluopyram, so that the activity on tobacco diseases can be obviously improved. The invention provides a novel compound for preventing and treating fungal diseases of plants.

Description

Technical Field

[0001] This invention belongs to the field of plant disease control technology, specifically relating to the application of an acridine derivative in the control of fungal diseases in tobacco and rice. Background Technology

[0002] Currently, chemical pesticides remain the most effective and economical way to control plant fungal diseases. However, due to the long-term and extensive use of traditional fungicides, pathogens have developed significant resistance to these agents, leading to a decline in the control efficacy of many commercially available fungicides. Furthermore, the widespread use of traditional pesticides also poses certain threats to the ecological environment, human health, and sustainable agricultural development. Therefore, developing novel, highly efficient, and environmentally friendly compounds is of great significance for the control of plant fungal diseases.

[0003] Acridine compounds have attracted widespread attention in medicine, chemistry, and physics due to their unique nitrogen heterocyclic structure and diverse biological activities. Several derivatives with acridine skeletons have been developed, exhibiting varying degrees of antibacterial, antiviral, and antitumor activities. These derivatives possess broad application prospects due to their structural stability and numerous substitution sites; however, research on their application in the control of plant fungal diseases is relatively limited, leaving considerable room for further development. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides an acridine derivative that has good control efficacy against fungal diseases in tobacco and rice.

[0005] Another object of the present invention is to provide a composition containing the above-mentioned compounds that has a synergistic effect on tobacco and rice diseases.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] The acridine derivative A9TC is used as an agricultural fungicide. The chemical structural formula of the acridine derivative A9TC is as follows: .

[0008] The acridine derivative A9TC can be synthesized by methods in the prior art or obtained commercially.

[0009] The target of the fungicide is *Trichophyton mentagrophytes* (Cucurbita spp.). Cucumber beetle Rhizoctonia solani ( ), Rhizoctonia solani Rhizoctonia solani Alternaria alternata ( ) Alternaria alternata Rice blast fungus ( Magnaporth rice ).

[0010] The preferred crops for which the fungicide is applied are tobacco or rice.

[0011] A pesticide composition comprising an acridine derivative A9TC and a succinate dehydrogenase inhibitor. Preferably, the succinate dehydrogenase inhibitor is selected from fluopyram, and the mass ratio of A9TC to fluopyram is 1:9-9:1. Preferably, the mass ratio of the acridine derivative A9TC to fluopyram is 1:9-3:7.

[0012] Preferably, the diseases controlled by the above-mentioned derivatives and compositions are tobacco target spot, tobacco red spot, rice sheath blight, and rice blast. More preferably, the diseases controlled are tobacco target spot and tobacco red spot.

[0013] The present invention has the following advantages: The acridine derivative A9TC provided by this invention exhibits significant inhibitory activity against major pathogenic fungi of tobacco and rice. Its synergistic effect with fluopyram significantly enhances its activity against tobacco diseases. This invention provides a novel compound for the control of plant fungal diseases. Attached Figure Description

[0014] Figure 1 It is an acridine derivative A9TC 1 H NMR spectrum. Detailed Implementation

[0015] The present invention will be further described below with reference to the embodiments and accompanying drawings, but the present invention is not limited to the following embodiments.

[0016] Example 1: Indoor toxicity of acridine derivative A9TC against tobacco and rice pathogenic fungi The structural formula of the acridine derivative A9TC is as follows: ; Purchased from Shanghai Taoshu Biotechnology Co., Ltd., purity: 93.8%. 1 H NMR image as follows Figure 1 As shown.

[0017] The mycelial growth rate method was used to determine the indoor toxicity of the acridine derivative A9TC against major pathogenic fungi of tobacco and rice. The specific procedure is as follows: (1) Isolation of pathogenic strains Diseased leaves with obvious symptom characteristics, collected from major tobacco and rice producing areas in Jiangxi Province, were used to isolate and purify the pathogen using the water agar method. After five purification cycles, the pathogen of tobacco target spot disease, *Trichophyton spp.*, was finally obtained. Thanatephorus cucumber The pathogen of tobacco red spot disease is Alternaria alternata (Alternaria). Alternaria alternata The pathogen of rice sheath blight is Rhizoctonia solani (Rhizoctonia solani). Rhizoctonia solani ) and rice blast fungus ( Magnaporthe riceFour pathogens, including , were used for subsequent indoor toxicity testing of compounds.

[0018] (2) Preparation of drug-containing culture medium Accurately weigh the acridine derivative A9TC and dissolve it in DMSO solution to prepare a stock solution. Then, dilute it to the target concentration with 0.1% Tween-80 aqueous solution. Mix the diluted solution and sterilized PDA medium at a volume ratio of 1:9 (drug solution: medium) to prepare a drug-containing medium with a target concentration of 50 μg / mL. Add the same volume of 0.1% Tween-80 to the blank control. Commercially available azoxystrobin (25% suspension) and jinggangmycin (4% aqueous solution) were directly diluted to the target concentration with 0.1% Tween-80 aqueous solution.

[0019] (3) Toxicity determination Taking *Tobacco Target Spot Pathogen* as an example, the specific method is as follows: *Tobacco Target Spot Pathogen* was inoculated onto PDA plates and pre-cultured for 5 days. Mycelial cakes were created at the edge 1 / 3 of the colony using a 5 mm diameter punch. These mycelial cakes were then transferred to drug-containing and blank PDA media, respectively, and incubated at 28℃ for 3 days. Each treatment was repeated 3 times. When the mycelia of the blank control covered 2 / 3 of the culture medium, the colony diameter was measured using the cross-sectional method, and the average value was calculated. The inhibition rate of the compound on the mycelia was then calculated. .

[0020] Table 1. Indoor toxicity of acridine derivative A9TC against four pathogenic fungi. Table 1 shows that acridine derivative A9TC exhibits good inhibitory effects against various plant pathogenic fungi, including *Tobacco Target Spot Fungus*, *Tobacco Red Spot Fungus*, *Rice Sheath Blight Fungus*, and *Rice Blast Fungus*, demonstrating broad-spectrum antifungal activity. At the same concentration (50 μg / mL), the inhibitory activity of acridine derivative A9TC against the four pathogenic fungi was significantly higher than that of the commercially available fungicide jinggangmycin. Furthermore, the inhibitory effects of acridine derivative A9TC against *Tobacco Target Spot Fungus*, *Tobacco Red Spot Fungus*, and *Rice Sheath Blight Fungus* were slightly higher than those of the commercially available fungicide azoxystrobin. In conclusion, acridine derivative A9TC, as a potential lead compound, has high application potential and development value in the control of major fungal diseases in tobacco and rice.

[0021] Example 2: Indoor synergistic virulence of acridine derivative A9TC in combination with *Tobacco Target Spot*. 1. Tobacco target spot pathogen The mycelial growth rate method was used to determine the combined toxicity in vitro. *Tobacco target spot pathogen* was inoculated onto PDA plates and pre-cultured for 5 days. Mycelial cakes were then created at the edges of the colonies using a 5 mm diameter punch, and subsequently transferred to a series of plates containing different concentrations of the fungicide and incubated for 3 days. Each treatment was repeated three times. After 3 days, the colony diameter was examined, and the inhibition rate on mycelia was calculated. The EC50 of each fungicide was calculated using SPSS software. 50 Values ​​were used to establish a virulence regression equation and R0. 2 EC 50 At a 95% confidence limit, the combined effect of acridine derivative A9TC and fluopyram was determined by the Wadley method, and the synergistic coefficient SR was calculated. SR < 0.5 was considered antagonistic, SR > 1.5 was considered synergistic, and SR between 0.5 and 1.5 was considered additive.

[0022] ; ; Where a and b represent the proportions of the two agents in the mixture, respectively.

[0023] Table 2. Combined toxicity of acridine derivative A9TC and fluopyram against *Tobacco Target Spot*. Table 2 shows that the combined use of acridine derivative A9TC and fluopyram exhibits good inhibitory effects against *Tobacco Target Spot*, with the inhibitory activity of the combined use being higher than that of either agent alone. At different mixing ratios, the synergistic coefficients ranged from 0.8427 to 1.8787, demonstrating an additive to synergistic effect; notably, the synergistic coefficient was 1.8787 at a mixing ratio of 3:7, showing a significant synergistic effect. In conclusion, the combined use of acridine derivative A9TC and fluopyram can effectively inhibit the growth of *Tobacco Target Spot*. This combined use can reduce the amount of commercially available pesticides used and delay the development of resistance when pesticides are used alone.

[0024] 2. Tobacco star bacterium The combined virulence of acridine derivative A9TC and fluopyram against tobacco target spot pathogens was determined according to the method for combined virulence assay of tobacco target spot pathogens.

[0025] Table 3. Combined toxicity of acridine derivative A9TC and fluopyram against *Acer tumefaciens*. Table 3 shows that the combined use of acridine derivative A9TC and fluopyram exhibits superior inhibitory activity against *Acer tumefaciens* compared to either agent alone. At different mixing ratios, the synergistic coefficients ranged from 0.8782 to 1.7872, all demonstrating varying degrees of synergistic effect. The synergistic coefficient was 1.7872 at a mixing ratio of 1:9, showing a significant synergistic effect. These results indicate that the combined use of acridine derivative A9TC and fluopyram has potential application in inhibiting the proliferation of *Acer tumefaciens*.

Claims

1. The application of an acridine derivative in the control of plant fungal diseases, characterized in that, The chemical structural formula of the acridine derivative is as follows: ； The acridine derivative targets *Trichophyton mentagrophytes* (a type of fungus). Thanatephorus cucumeris Rhizoctonia solani ( ) Rhizoctonia solani Alternaria alternata ( ) Alternaria alternata ) or rice blast fungus ( Magnaporthe oryzae ).

2. The application according to claim 1, characterized in that, The crops targeted by the acridine derivatives are tobacco or rice.

3. The application according to claim 1 or 2, characterized in that, The diseases to be controlled are tobacco target spot, tobacco red spot, rice sheath blight, or rice blast.

4. The application according to claim 1 or 2, characterized in that, The diseases to be controlled are tobacco target spot disease or tobacco red spot disease.

5. A pesticide composition, characterized in that, The active ingredient is and fluopyram; The mass ratio of fluopyram to fluopyram is 1:9-9:

1.

6. The pesticide composition according to claim 5, characterized in that, The mass ratio of fluopyram to fluopyram is 1:9-3:

7.

7. The pesticide composition according to claim 5 or 6, characterized in that, The pesticide composition is used to control tobacco target spot, tobacco red spot, rice sheath blight, or rice blast.

8. The pesticide composition according to claim 5 or 6, characterized in that, The pesticide composition controls tobacco target spot disease or tobacco red spot disease.

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