Mitochondrial Porin Is Required for Versatile Biocontrol Trait-Involved Biological Processes in a Filamentous Insect Pathogenic Fungus

The mitochondrial voltage-dependent anion channel (VDAC) is the major channel in the mitochondrial outer membrane for metabolites and ions. VDACs also regulate a variety of biological processes, which vary in the number of VDAC isoforms across different eukaryotes. However, little is known about VDAC-mediated biocontrol traits in biocontrol fungi. Here, the only VDAC isoform (BbOmm1) in the filamentous insect pathogenic fungus Beauveria bassiana was characterized, which was crucial for maintenance of mitochondrial homeostasis and function and important biocontrol traits. Besides serious impairment of fungal growth, conidiation, and germination, inactivation of BbOmm1 led to increased sensitivity/tolerance to oxidative and osmotic stresses and production of oosporein and other secondary metabolites, which corresponded to the mitochondrial damage, downregulation of membrane lipid and cell wall homeostasis-involved genes, and upregulation of detoxification genes and biosynthesis gene clusters of those metabolites. These results enrich our understanding of VDAC-mediated biocontrol traits in insect fungal pathogens.