additive contributions of two manganese-cored superoxide dismutases (mnsods) to antioxidation, uv tolerance and virulence of beauveria bassiana添加剂的贡献两个manganese-cored超氧化物歧化酶(mnsods)抗氧化作用,紫外线宽容和白僵菌的毒性.pdfVIP

Additive Contributions of Two Manganese-Cored Superoxide Dismutases (MnSODs) to Antioxidation, UV Tolerance and Virulence of Beauveria bassiana Xue-Qin Xie, Fang Li, Sheng-Hua Ying, Ming-Guang Feng* Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People’s Republic of China Abstract The biocontrol potential of entomopathogenic fungi against arthropod pests depends on not only their virulence to target pests but tolerance to outdoor high temperature and solar UV irradiation. Two Beauveria bassiana superoxide dismutases (SODs), BbSod2 and BbSod3, were characterized as cytosolic and mitochondrial manganese-cored isoenzymes (MnSODs) dominating the total SOD activity of the fungal entomopathogen under normal growth conditions. To probe their effects on the biocontrol potential of B. bassiana, DBbSod2, DBbSod3, and three hairpin RNA-interfered (RNAi) mutants with the transcripts of both BbSod2 and BbSod3 being suppressed by 91–97% were constructed and assayed for various phenotypic parameters in conjunction with DBbSod2/BbSod2, DBbSod3/BbSod3 and wild-type (control strains). In normal cultures, the knockout and RNAi mutants showed significant phenotypic alterations, including delayed sporulation, reduced conidial yields, and impaired conidial quality, but little change in colony morphology. Their mycelia or conidia became much more sensitive to menadione or H O -induced oxidative stress but had little change in sensitivity to the hyperosmolarity of NaCl 2 2 and the high temperature of 45uC. Accompanied with the decreased antioxidative capability, conidial tolerances to UV-A and UV-B irradiations were reduced by 16.8% and 45.4% for DBbSod2, 18.7% and 44.7% for DBbSod3, and ,33.7% and ,63.8% for the RNAi mutants, respectively. Their median lethal times (LT50s) agains