Abstract:

【Objective】 Biocontrol potential of strain TY009 was assessed in the round by its antagonism against Rhizoctonia solani as well as Magnaporthe oryza and Ustilaginoidea virens, including the effect of pH and heat on its stability of gliotoxon. 【Method】 Gliotoxin was seperated from liquid media of Trichoderma virens strain TY009 and it was purified by chromatographic methods. Antagonistic action of strain TY009 against R. solani was determined by dual culture assay. The inhibitory activities of gliotoxin against the hypha growth and sclerotial germination of R. solani, conidial germination and appressorial formation of M. oryza and conidial germination and secondary conidium formation of U. virens, were assessed in laboratory, including the effects of heat and pH on bioactivity of gliotoxin. 【Result】 The antagonism of strain TY009 against R. solani was significant. The inhibitory activities of gliotoxin demonstrated that there was no hypha growth of R. solani in 150 μg•mL-1 of gliotoxin solution and sclerotial germination which was treated for 4 h in 160 μg•mL-1. There was no conidial germination and appressoria formation of M. oryza in 50 and 10 μg•mL-1of gliotoxin solution, respectively, and no conidial germination and secondary spore formation of U. virens in 1.0 μg•mL-1. The bioactivity of gliotoxin against the hyphae of R. solani did not change at 100℃ for 1 h, but in condium suspension of U. virens with 0.5 μg•mL-1 of gliotoxin, the bioactivity of gliotoxin against conidial germination and secondary conidium formation was not significant in the conidium suspension with a pH greater than 6.0 and significant with low pH. 【Conclusion】 T. virens strain TY009 possesses multiple mechanisms of antifungal activity and it is considered to be a potential biological control agent for biocontrol of rice sheath blight and, rice blast and rice false smut

Key words: Trichoderma virens, biocontrol, rice sheath blight, rice blast, rice false smut