产孢是杀虫真菌繁殖的主要方式，与真菌农药的生产效率直接相关。丝状真菌通常具有正常产孢和微循环产孢两种产孢方式，但调控产孢方式转换的机制尚不清楚。本课题组已建立蝗绿僵菌微循环产孢培养条件，并利用抑制消减杂交技术获得了微循环产孢上调表达的精氨酸酶基因MaAGA，敲除该基因后蝗绿僵菌无法进行微循环产孢，表明精氨酸代谢途径在蝗绿僵菌的产孢方式转换过程中起重要作用。本项目拟敲除、回复以及超表达蝗绿僵菌中精氨酸代谢途径的相关基因，通过分析酶活和代谢产物含量与蝗绿僵菌产孢方式的关系，以及外加相关代谢产物和酶抑制剂对蝗绿僵菌产孢方式的影响等，鉴定出该途径中调控蝗绿僵菌产孢方式转换的关键基因和关键代谢产物；并明确精氨酸代谢途径相关基因对蝗绿僵菌重要性状的影响。阐明精氨酸代谢途径调控蝗绿僵菌产孢方式转换的作用机制。该结果将为阐明丝状真菌产孢方式转换的机制提供理论依据，为提高杀虫真菌农药生产效率提供技术途径。

Conidiation is the main mode of asexual reproduction in entomopathogenic fungi, directly related with the productivity of fungal insecticides. Filamentous fungi usually have two conidiation patterns: normal conidiation and microcycle conidiation. However, the regulatory michanism of the conidiation pattern shift in filamentous fungi is still not clear. In our previous studies, a medium induced the microcycle conidiation of Metarhizium acridum was established. To reveal the regulatory mechanism of the conidiation pattern shift in M. acridum, 221 up-regulated genes during microcycle conidiation were screened by suppression subtractive hybridization. In these differentially expressed genes, an arginase gene, designated as MaAGA, was identified. The conidiation pattern can be shifted from the microcycle conidiation to the normal conidiation on microcycle conidiation medium after deleted MaAGA in M. acridum. This result indicated that the arginine metabolism played critical roles during the conidiation pattern shift in M. acridum. In this project, the genes related to the arginine metabolism in M. acridum will be knocked out, complemented and overexpressed. And the conidiation properties of all the knockout, complemented and overexpressed transformants will be investigated to identify the important genes for microcycle conidiation in the arginine metabolism pathways. The contents of some arginine metabolites and the activities of enzymes related to the arginine metabolism will be assayed in M. acridum. To identify the critical arginine metabolites during microcycle conidiation of M. acridum, the relationship between the arginine metabolites and conidiation pattern shift will be analyzed. Moreover, the conidiation pattern of various fungal strains in the medium supplemented with some arginine metabolites or some inhibitors of enzymes related to the arginine metabolism will be examined to confirm the critical metabolites and enzymes during conidiation pattern shift in M. acridum. In additon, the functions of the genes related to the arginine metabolism in M. acridum in stress tolerances and virulence will also be clarified. Taken together, the mechanism of the arginine metabolism pathways regulating conidiation pattern shift would be elucidated in M. acridum. These results will provide essential information about the mechanism of the regulation of the conidiation pattern shift in filamentous fungi. And the knowledge will provide theoretical foundation and candidate genes for developing stable, high-efficiency mycoinsecticide.