Induction of Thiram-resistant Isolates and Chitinase Biocontrol Properties of Trichoderma harzianum

Four mutants of Trichoderma harzianum Th-30 were obtained by UV-light and thiram stress on PDA medium.They were resistant to thiram and could grow normally on the medium mixed with thiram of 2.0×105μg/L.The result of toxicity test showed that EC50 of thiram for the mutants were 10 times higher than their parent strain Th-30.A mutant,UV-4,could grow well in in high thiram stress and produce biocontrol functional chitinase,which inhibited 85.43% of sporulation and 68.88% of pathogenicity of Colletotrichum lagenarium,causing cucumber anthracnose,and degrade cell wall of the pathogen.The mutant was stable genetically,suggesting that it should have the potential to be mixed with thiram for vegetable disease control.