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.