绿僵菌GPCR介导的寄主识别及专化性形成机理研究

Environmentally friendly entomopathogenic fungi such as Metarhizium and Beauveria species play important roles in regulation of insect population and pest biocontrol. Unlike Beauveria species, the species of Metarhizium could be divided into two different host range groups: the generalists that can infect a broad range of insects and the specialist species that can only kill a particular lineage of insects. It is still unclear how and why the pathogenic fungi recognize and infect different insect hosts. Based on our previous comparative genomic studies, we found a significant gene number expansion phenomenon in the genome of the geneneralist Metarhizium robertsii when compared to the locust-specific M. acridum. Especially, the putative genes involved in host recognition, adaptation and specialization, i.e., the G protein-coupled receptor (GPCR) subfamilies in M. robertsii are expanded. In this study, we will use different molecular biology skills such as gene deletion, gene exchange (heterologous expression) to functionally study the GPCRs between the M. robertssi and M. acridum, aiming to understand how the GPCRs regulate the induction of the infection structure appressorium differentiation and activation different signaling pathways. By clarifying the molecular mechanism of how Metarhizium species using GPCRs to achieve their host recognition and specialization, the results will provide the support for the alleviation of safety concerns and technical improvements of the cost-effective application mycoinsecticides.

以绿僵菌及白僵菌等为代表的环境友好型杀虫真菌在昆虫种群自然调控及害虫持续控制中发挥着重要的作用。不同于白僵菌，绿僵菌种类多样，就杀虫范围来说，可分为广谱性绿僵菌和寄主种类高度专化性绿僵菌两大类。杀虫真菌如何识别不同寄主并启动不同信号途径的感染机理仍不清楚。我们前期完成了不同绿僵菌的比较基因组研究，发现寄主广谱的罗伯茨绿僵菌较蝗虫专化的蝗绿僵菌而言存在显著的基因扩张现象，即前者编码有更多的不同蛋白家族基因，包括G蛋白偶联受体（GPCR）基因，推测与寄主识别、适应及专化性形成有关。本研究针对两种绿僵菌的不同GPCR亚家族基因，开展系列GPCR基因的缺失、基因互换、侵染结构诱导及不同信号途径的诱导启动研究，以期阐明GPCR介导的绿僵菌寄主识别及专化性形成机制。预期研究成果有利于揭示病原真菌寄主识别的分子机理，同时为真菌杀虫剂的安全、高效应用提供理论及技术支撑。