Transformation of the endochitinase gene Chi67 1 in Clonostachys rosea 67 1 increases its biocontrol activity against Sclerotinia sclerotiorum
Clonostachys rosea is a promising biocontrol fungus active against various plant fungal pathogens. In this study, the endochitinase encoding gene Chi67 1, the expression of which is sharply upregulated in C. rosea 67 1 when induced by sclerotia, was transformed into the original isolate by protoplast transformation, and transformants were screened against Sclerotinia rot of soybean. The transformation efficiency was approximately 50 transformants per 1 x 107 protoplasts, and 68 stably heritable recombinants were assayed. The parasitic rates of 32.4% of the tested strains increased by more than 50% compared to 43.3% of the wild type strain in 16 h, and the Rc4 4 transformant showed a parasitic rate of 100% in 16 h. The control efficiencies of the selected efficient transformants to soybean Sclerotinia stem rot were evaluated in pots in the greenhouse, and the results revealed that Rc4 4 achieved the highest efficiency of 81.4% which was 31.7% and 28.7% higher than the control achieved by the wide type and the pesticide carbendazim, respectively. Furthermore, the expression level of Chi67 1 was 107 fold higher in Rc4 4 than in the wild type, and accordingly, the chitinase activity of the recombinant increased by 140% The results lay a foundation for the development of efficient genetically engineered strains of C. rosea.
AMB Express