Use of an acridine derivative for the control of fungal diseases of plants

Abstract

The application belongs to the technical field of plant disease prevention and treatment, and provides application of an acridine derivative in prevention and treatment of plant fungal diseases. The acridine derivative provided by the application has obvious inhibitory activity on main pathogenic fungi of tobacco and rice, and the compounding of the acridine derivative with fluopyram has a synergistic effect, which can significantly improve the activity on tobacco diseases. The application provides a new compound for prevention and treatment of plant fungal diseases.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of plant disease control, and particularly relates to application of an acridine derivative in prevention and treatment of tobacco and rice fungal diseases. BACKGROUND

[0002] At present, chemical pesticides are still the most effective and economical way to prevent and treat plant fungal diseases. However, due to the long-term and large-scale use of traditional fungicides, the resistance of pathogenic fungi to existing fungicides has significantly increased, resulting in a decrease in the control effect of many commercial fungicides on diseases. In addition, the large-scale use of traditional fungicides has also caused certain threats to the ecological environment, human health and sustainable development of agriculture. Therefore, it is of great significance to develop new, efficient and environmentally friendly compounds for the prevention and treatment of plant fungal diseases.

[0003] Acridine compounds have attracted widespread attention in the fields of medicine, chemistry and physics due to their unique nitrogen heterocyclic structure and diverse biological activities. Some derivatives with acridine skeleton structure have been developed, which exhibit different degrees of antibacterial, antiviral, antitumor and other activities. Due to the characteristics of stable structure, multiple substitution positions, etc., these derivatives have broad application prospects, but the research on their prevention and treatment of plant fungal diseases is relatively limited, and there is still a large space for expansion. SUMMARY

[0004] In view of the problems in the prior art, the application provides an acridine derivative which has good prevention and treatment effect on tobacco and rice fungal diseases.

[0005] Another object of the application is to provide a composition containing the above-mentioned compound, which has a synergistic effect on tobacco and rice diseases.

[0006] To achieve the above object, the application adopts the following technical solutions.

[0007] The application of the acridine derivative A9TC as an agricultural fungicide, wherein the chemical structural formula of the acridine derivative A9TC is as follows:

[0008] .

[0009] The acridine derivative A9TC can be synthesized by the method in the prior art or obtained by commercial purchase.

[0010] The target of the fungicide is Guignardia bidwellii (Cooke) Vink, Thanatephorus cucumeris Rhizoctonia solani Kuhn, Rhizoctonia solani Alternaria alternata (Fr.) Keissler, Alternaria alternata Magnaporthe grisea (Hebert) Barr, Magnaporthe oryzae Figure 1 .

[0011] The control crop of the fungicide is preferably tobacco or rice.

[0012] A pesticide composition, the effective component of which is acridine derivative A9TC and 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.

[0013] Preferably, the above-mentioned derivatives and compositions control diseases such as target spot of tobacco, brown spot of tobacco, sheath blight of rice and rice blast. More preferably, the diseases controlled are target spot of tobacco and brown spot of tobacco.

[0014] The present application has the following advantages:

[0015] The acridine derivative A9TC provided by the present application has obvious inhibitory activity on the main pathogenic fungi of tobacco and rice, and the combination of A9TC and fluopyram has a synergistic effect, which can significantly improve the activity on tobacco diseases. The present application provides a new compound for the prevention and treatment of plant fungal diseases. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the acridine derivative A9TC 1 H NMR spectrum. DETAILED DESCRIPTION

[0017] The present application will be further described below in conjunction with examples and drawings, but the present application is not limited by the following examples.

[0018] Example 1: In vitro toxicity of acridine derivative A9TC on pathogenic fungi of tobacco and rice

[0019] The structural formula of the acridine derivative A9TC is as follows:

[0020] ;

[0021] Purchased from Shanghai Taotuo Biotechnology Co., Ltd., purity: 93.8%, its 1 H NMR spectrum is as Thanatephorus cucumeris shown.

[0022] The in vitro toxicity of acridine derivative A9TC on the main pathogenic fungi of tobacco and rice was determined by mycelial growth rate method, and the specific process was as follows:

[0023] (1) Isolation of pathogenic strains

[0024] The diseased leaves with obvious disease characteristics collected from the main tobacco and rice production areas in Jiangxi Province were used to isolate and purify the strains by water agar method. After 5 times of purification, the pathogenic fungus of target spot of tobacco, Peronophythora litchii, was finally obtained. Alternaria alternata Rhizoctonia solaniThe pathogen of tobacco red spot disease is Alternaria alternata (Alternaria). Magnaporthe oryzae The pathogen of rice sheath blight is Rhizoctonia solani (Rhizoctonia solani). ​ ) and rice blast fungus ( ​ Four pathogens, including , were used for subsequent indoor toxicity testing of compounds.

[0025] (2) Preparation of drug-containing culture medium

[0026] 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.

[0027] (3) Toxicity determination

[0028] 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.

[0029] .

[0030] Table 1. Indoor toxicity of acridine derivative A9TC against four pathogenic fungi.

[0031]

[0032] 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.

[0033] Example 2: Indoor synergistic virulence of acridine derivative A9TC in combination with *Tobacco Target Spot*.

[0034] 1. Tobacco target spot pathogen

[0035] 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.

[0036] ;

[0037] ;

[0038] Where a and b represent the proportions of the two agents in the mixture, respectively.

[0039] Table 2. Combined toxicity of acridine derivative A9TC and fluopyram against *Tobacco Target Spot*.

[0040]

[0041] 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.

[0042] 2. Tobacco Star Bacteria

[0043] 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.

[0044] Table 3. Combined toxicity of acridine derivative A9TC and fluopyram against *Acer catarrhalis*.

[0045]

[0046] 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 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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