研究昆虫病原真菌的致病机理可为提高真菌杀虫剂的效率提供理论支撑。穿透昆虫体壁是启动致病过程的关键步骤，成功与否决定感染能否进行下去。罗伯茨绿僵菌是研究昆虫病原真菌致病机理的模式材料；在前期工作中，项目组发现了调控该菌穿透昆虫体壁的新转录因子AFTF1和AFTF2和调控它们的部分上游基因，这些组分构成了控制穿透昆虫体壁的两个新调控通路的雏形。本项目将进一步完善这两个调控通路，研究通路内的调控机制及通路间的关系，并研究受通路调控的新致病基因的作用机制。包括三个研究内容。其一，挖掘调控AFTF1和AFTF2的更多上游组分，并研究它们对AFTF1和AFTF2的调控机制。其二，研究受AFTF1和AFTF2控制的下游调控组分和控制机制；并研究两个通路间的关系。其三，研究上述调控通路所控制的新致病基因的作用机制。完成本项目将揭示控制罗伯茨绿僵菌穿透昆虫体壁的新调控通路，加深对其致病机理的认识。

Application of mycoinsecticides can reduce the amount of chemical insecticides used for pest control, protecting environments. However, the slow killing speed of mycoinsecticides is limiting their widespread usage. Understanding of how entomopathogenic fungi infect insects provides theoretical bases for improving efficacy of mycoinsecticides. Penetration of the insect cuticle is the initial step in pathogenesis and determines whether or not the infection is successful. Metarhizium robertsii has been used as a model for studying fungal pathogenesis in insects. In our previous studies, we identified two new transcription factors that are necessary for the fungus to penetrate the insect cuticle, and they were regulated by Slt2-MAPK, Fus3-MAPK or the membrane protein Mr-OPY2, forming novel circuits for regulating cuticle penetration. In this proposal, we will identify more components in the regulatory circuits, reveal the molecular interactions between the components and profile the downstream pathogenicity genes regulated by the circuits. We have three research aims in this proposal. First, we will identify the upstream components that regulate AFTF1 and AFTF2 and elucidate the regulatory mechanisms. Secondly, we will identify regulatory components, such as transcription factors and signaling pathways, which are controlled by AFTF1 or AFTF2, and reveal mechanisms for AFTF1 and AFTF2 to regulate these components. Finally, we will functionally characterize novel pathogenicity genes controlled by the above regulatory circuits. Completion of this project will provide significant insights into mechanisms for M. robertsii to penetrate the insect cuticle and advances our understanding of how the fungus infects insects.