Metarhizium acridum Raw sequence reads

Conidiation capacity and conidial quality are very important for the production and application of mycopesticides. Most filamentous fungi have two conidiation. Conidiation through microcycle conidiation proceeds to more rapidly achieve a maximum of conidial yield than normal conidiation and hence is of greater merit for exploitation in mass production of fungal insect pathogens, such as Metarhizium acridum. In this study, the mechanism underlying conidiation pattern shift in M. acridum was explored by characterization of the fungal homeobox gene MaH1. MaH1 was evidently localized to the nuclei of hyphae and transcriptionally expressed at a maximal level when conidiation began. Intriguingly, deletion of MaH1 in M. acridum resulted in a shift of normal conidiation to microcycle conidiation on a medium, and hence accelerated conidiation and increased conidial yield. In the deletion mutant, moreover, conidia became larger in size and hyphae cells were shorter in length during the conversion process while conidial virulence and stress tolerance were not altered. Unveiled by digital gene expression profiling, MaH1 controls the shift of conidiation patterns by mediating a set of genes related to hyphal growth, cell differentiation, conidiation and some important signaling pathways. These findings indicate that MaH1 and its downstream genes can be exploited to increase conidial yield for more efficient production of mycopesticides.