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.