球孢白僵菌生物防治潜能必需的无性循环的分子调控机理

Various formulations of Beauveria bassiana widely applied for the control of crop and forest insect pests are fungical insecticides comprising the active ingedients of conidia for insect infectiion and easy dispersion. Thus, conidial production (yield) and maturity (quality) regulated by three activators in central developmental pathway and seven transcription factors upstream or downstream of the pathway are determinant to the biological control potential of the formulations. However, all the regulators are functionally unexplored in either B. bassiana or other fugnal entomopathogens. Evolutionary and developmental features of B. bassiana suggest a possible specialty in the regulation of the fungal asexual cycle. The project proposed on the basis of our prevous findings seeks to characterize the fungctions of each regulator by multi-phenotypic analyses of single-gene deletion and complementary rescued mutants and to elucidate what regulators are directly or indirectly involved in the control of conidial production and maturation, how the control is achieved, and what cellular events are associated with the developmental control. An emphasis is placed on the relationship of different conidial maturity with conidial virulence and multi-stress tolerance and hence on the estiablishment of a set of indices for proper maturity of conidia. The results achieved by the implementation of the project are expected to reveal molecular mechansims involved in asexual cycle regulation of B. bassiana and hence to benefit an improvement of mass-production technology that may maximize conidial yield and quality for the production of fungal insecticides.

球孢白僵菌制剂是广泛用于农林害虫防治的真菌杀虫剂，有效成分为侵染性和扩散性的分生孢子，后者产量和质量在很大程度上决定制剂的生物防治潜能。分生孢子形成(产量)和成熟(质量)过程是由中心发育通路中的三个激活子及其上下游的七个转录因子所调控的，而它们在球孢白僵菌中的功能未知。球孢白僵菌有较为独特的进化和发育特征，预示其无性发育的调控模式也可能有特殊性。基于前期工作基础，本项目拟通过基因敲除和回补菌株的多表型分析、转录互作分析、生化分析和细胞生物学分析，系统解析球孢白僵菌中心发育通路及其上下游各个转录因子的生物学功能，揭示支配分生孢子形成与成熟的调控因子、调控途径及其关联的细胞生物学事件，揭示分生孢子的成熟度与毒力及抗逆力的关系，建立表征成熟度恰当的分生孢子质量指标，为设计高产优质的孢子粉生产工艺提供科学依据。

本项目通过基因敲除和回补菌株的多表型分析、生理生化分析、细胞生物学分析及组学分析，系统解析了球孢白僵菌中心发育通路关键激活子与40余个孢子产量及质量相关基因的生物学功能，揭示了支配分生孢子形成与成熟的调控因子、调控途径及其关联的细胞生物学事件，揭示了分生孢子质量即成熟度与毒力及抗逆力之间的关系。这些成果充分证明作为真菌杀虫剂有效成份的球孢白僵菌分生孢子的形成与成熟是受中心发育通路调控的细胞生物学事件，充分证明其菌丝侵入昆虫血腔后转化为单细胞芽生孢子而加快寄主僵死速度的两型转化也是受中心发育通路调控的细胞生物学事件，充分证明球孢白僵菌中心发育通路的激活及上游调控途径的多样化、复杂性及特殊性。这些成果实现并超越了预期目标，为进一步深入研究奠定了坚实基础，亦为利用无性发育调控机理设计高产优质的孢子粉生产工艺提供了科学依据。迄今共发表标注本项目批准号的SCI论文24篇（第一标注18篇及第二标注5篇），五年综合影响因子平均每篇达到4.49，已累计被引用180篇次。获发明专利授权2项，申请发明专利4项。培养毕业博士生10人和硕士生6人。