The antifungal activity and toxicity of new type polyene macrolide antibiotics-Antifungalmycin 702 and Fungichromin against Rhizoctonia solani,Helminthosporium sigmoideum Cav. ,Magnaporthe grisea and Ustilaginoidea virens were studied by mycelial growth rate method and mycelial dry weight method in vitro. The results showed that both of Antifungalmycin 702 and Fungichromin had strong antifungal activity against four speices of rice pathogenic fungi. Treated with 50 μg / mL Antifungalmycin 702 ,the inhibitory rates of Antifungalmycin 702 against R. solani,H. sigmoideum Cav. ,M. grisea and U. virens were 100% 、 100% 、91. 20% and 68. 10% ,and EC 50 and EC 90 were 7. 00,10. 30,14. 41,26. 71 and 13. 20,17. 66,27. 67,128. 28 μg / mL,respectively. Treated with 13 μg / mL Fungichromin,the inhibitory rates of Fungichromin against four speices of rice pathogenic fungi were 78. 20% ,100% ,100% and 79. 17% ,and EC 50 and EC 90 were 1. 47,1. 91,2. 37,0. 20 and 41. 05,3. 92,4. 34,135. 54 μg / mL,respectively. The antifungal activity of Fungichromin was stronger than Antifungalmycin 702.
Hui LUMeiping WENSaijin WEIXiaorong TUJia XUGuoquan TU
In order to study the inhibition mechanism of antifungal monomers DZP8 produced by streptomyces 702 strain against Rhizoctonia solani, the effects of DZP8 on mycelial morphology were investigated under light microscope, and the effects of DZP8 on mycelial inclusion leakage and cell membrane damage of mycelium were determined. The results showed that DZP8 caused a series of changes in mycelial morphology of R. solani in liquid culture condition. DZP8 treatments with concentrations of 1.81 and 3.35 μg/mL for 24 h caused big vacuole, rough surface and more inclusions of mycelium. With the treatment time prolonging, the mycelium distorted and appeared irregular constriction. DZP8 treatment with concentration of 20.10 μg/mL led to the increase of conductivity of mycelium culture liquid, leakage of soluble sugar and protein, and the lipid peroxidation of mycelium membrane. It was found that DZP8 at a very low concentration could cause changes of mycelial morphology of R. solani, while only a certain concentration could cause significant damage to cell membrane. This indicated that cell membrane might be one of the action sites of DZP8, and it might have other action sites or mechanism.
Lu HuiWen MeipingTu XiaorongXu JiaFeng HuagenTu Guoquan
[Objective] The paper was to study control effect and bio-control potential of 0.3% agricultural antibiotic 702 aqueous solution(AS) against Rhizoctonia solani,Magnaporthe grisea and Ustilaginoidea virens. [Method] The toxicity effect of 0.3% agricultural antibiotic 702 AS against R. solani,M. grisea and U. virens were studied by mycelial growth rate method and mycelial wet weight method. [Result] The EC50 and EC90 values of agricultural antibiotics 702 AS to R.solani,M. grisea and U. virens in vitro condition were 4.16 and 16.17 mg/L,16.05 and 41.85 mg/L,111.2 and 389.0 mg/L,respectively. Agricultural antibiotics 702 AS had good inhibition effect against R. solani and M. grisea and could basically achieve the effects of commercially available Jinggangmycin and kasugamycin,but the inhibition effect against U. virens was relatively weak. The preventive activity of aqueous solution was obviously higher than treatment activity.[Conclusion] 0.3% Agricultural antibiotic 702 AS is considered to be a potential biological control agent against R. solani,M. grisea and U. virens,and can be used as the potential alternative pesticide of Jinggangmycin.
