球孢白僵菌是广泛用于农林害虫生物防治的昆虫病原真菌，其被注释的基因组中约有25%的基因编码结构域未知或根本缺乏可辨识结构的假定蛋白，成为探索其致病杀虫分子遗传机制的障碍。前期球孢白僵菌与小菜蛾侵染互作的转录组分析显示，在接种后24、36和48小时三个关键时刻显著上调即可能在侵染过程中扮演重要角色的基因多达556个，其中近半数编码小分子疑似分泌蛋白PSP。本项目选择在非昆虫病原真菌中无同源物即最可能在侵染昆虫过程中发挥特殊作用的50余个编码缺乏可辨识结构域假定蛋白的PSP基因进行研究。通过基因敲除株、回补株及野生株的多表型实验和多层次分析，从中发掘对生物防治潜能重要性状具有突出贡献和调控作用的新信号因子或效应因子，筛选与之互作的信号蛋白或上游转录因子，研究揭示新信号因子的作用机理、新效应因子的表达调控机理及其细胞生物学事件，由此深化球孢白僵菌致病杀虫机理及生物防治潜能遗传背景的科学认识。

Beauveria bassiana is a classic entomopathogenic fungus widely applied in biological control programs of pest insects and mites. Its annotated genome contains up to 25% genes that encode hypothetical proteins with no recognizable domain or domains of unknown function and hence are obstacles to understanding molecular mechanisms involved in the fungal invasion and virulence. Our previous analysis of transcriptomes constructed in the infection course of B. bassiana against Plutella xylostella has unveiled 556 genes co-upregulated at 24, 36 and 48 h post inoculation. Of those, nearly half encode putative secretory proteins (PSP) likely involved in the fungal infection course. This project has two goals. The first goal is to discover new signalling factors or effectors crucial for biological control potential of B. bassiana by elucidating biological functions of about 50 PSP genes through multi-phenotypic analyses of their deletion/complement mutants in parallel with wild-type. The genes selected for study encode small hypothetical proteins without any recognizable domain, lack homologues in non-entomopathogenic fungi and hence are more likely involved in the fungal invasion. The second goal is to identify proteins and transcription factors that interact with the new signalling genes or mediate the new effector genes, to reveal cellular processes and events involved in their interactions and to explore possible mechanisms involved in their expression, regulation and function. The expected results include new virulence factors highly potential for use in genetic maintenance and improvement of fungal strains against arthropod pests and provide new insights into genetic mechanisms of B. bassiana pathogenicity and biocontrol potential.