绿僵菌双功能过氧化氢酶过氧化物酶(MaKatG1)基因影响菌株的毒力和抗紫外能力.docVIP

 MaKatG1, a bifunctional catalase-peroxidase gene, 5 10 15 20 25 30 35 40 contributes to virulence and UV tolerance of Metarhizium acridum# FAN Anni, PENG Guoxiong, XIA Yuxian** (Genetic Engineering Research Center, College of Bioengineering, Chongqing University, ChongQing 400030) Abstract: Entomopathogenic fungi are exposed to reactive oxygen species (ROS) produced either as a secondary products derived from a chemical reaction due to exposure to stress (UV, heat) or by the host. However, the mechanism by which fungal pathogens overcome the toxicity of ROS is unclear. In this study, a bifunctional catalase-peroxidase homolog, KatG1, was identified from Metarhizium acridum, a specific pathogenic fungus against locust. The knockout mutant of MaKatG1 exhibited reduced catalase and peroxidase activity and increased susceptibility to H2O2 and menadione, indicating that MaKatG1 has a bifunctional catalase-peroxidase acctivity and plays a role in the oxidative stress response. The germination and appressorium formation rates of the knockout mutant were decreased on locust wings, but were not affected in vitro. Compared with the wild-type, the virulence of the mutant was signi?cantly reduced following topical inoculation, but was not affected following injection. These results demonstrated that the MaKatG1 gene plays a role in the early stages of fungal infection including germination and appressorium formation. Furthermore, UV-B tolerance of the mutant was reduced. This study demonstrated that MaKatG1 contributes to virulence and UV-B tolerance. Keywords: Entomopathogenic fungi; Metarhizium acridum; bifunctional catalase-peroxidase; virulence; UV tolerance 0 Introduction Entomopathogenic fungi invade their hosts by direct penetration of the exoskeleton or cuticle. The infection process involves conidia adherence to the insect cuticle, germination, formation of appressorium, penetration of the cuticle, propagation in the hemocoel, finally causing death of the host (