Comparative RNAseq analysis of the insect-pathogenic fungus Metarhizium anisopliae reveals specific transcriptome signatures of infectious hyphal bodies (blastospores) and mycelial hyphae

Metarhizium anisopliae is a facultative entomopathogenic fungus used as biological control agent of several agricultural pests worldwide. It is a dimorphic fungus that is able to display two growth morphologies, i.e. a filamentous phase with formation of hyphae and a yeast-like phase with formation of single-celled blastospores. Blastospores play an important role for M. anisopliae pathogenicity during disease development. They are formed solely in the hemolymph of the insects as a fungal strategy to quickly multiply and colonize the insect´s body. Hyphae are vegetative structures that are formed as M. anisopliae grows in soil, associated with plants or inside killed insect hosts but does not require insects to be formed. Hyphae and blastospores can be produced in vitro under specific conditions and blastospores have great commercial potential for direct application in biological control. Here, we use comparative genome-wide transcriptome analyses to determine changes in gene expression between the filamentous and blastospore growth phases in vitro to characterize physiological changes and metabolic signatures associated with M. anisopliae dimorphism.

金龟子绿僵菌（Metarhizium anisopliae）是一种兼性昆虫病原真菌，在全球范围内被用作多种农业害虫的生物防治制剂。该真菌为二态型真菌，可呈现两种生长形态：一是形成菌丝（hyphae）的丝状生长相，二是形成单细胞芽生孢子（blastospores）的类酵母生长相。芽生孢子对金龟子绿僵菌在病害发展过程中的致病力具有重要作用，其仅在昆虫血淋巴（hemolymph）中形成，是真菌快速增殖并定殖昆虫体内的生存策略。菌丝作为营养生长结构，可在金龟子绿僵菌生长于土壤、植物关联环境或已死亡的昆虫宿主体内时形成，无需依赖昆虫宿主。菌丝与芽生孢子均可在体外特定条件下培养产生，且芽生孢子具备直接应用于生物防治的巨大商业潜力。本研究通过全基因组比较转录组分析，解析体外培养条件下丝状生长相与芽生孢子生长相之间的基因表达变化，以阐明金龟子绿僵菌二态性相关的生理变化与代谢特征。