The Mitogen-activated Protein Kinase Hog1 Regulates Fungal Development, Pathogenicity and Stress Response in Botryosphaeria dothidea

The high-osmolarity glycerol mitogen-activated protein kinase (HOG-MAPK) pathway plays a central role in environmental stress adaptation in eukaryotes. However, the biological function of HOG-MAPK pathway varies in different fungi. In this study, we investigated the HOG-MAPK pathway by inactivation of the core element Hog1 in Botryosphaeria dothidea, the causal agent of Botryosphaeria canker and apple ring rot. Targeted deletion of BdHOG1 resulted in the loss of conidiation ability and significant reduction of virulence. In addition, the ΔBdHog1 mutant exhibited hypersensitivity to osmotic stress, but resistance to phenylpyrrole and dicarboximide fungicides. Comparative transcriptome analysis revealed that inactivation of BdHog1 influenced multiple metabolic pathways in B. dothidea. Taken together, our results suggest that BdHog1 plays a crucial role in development, virulence and stress tolerance in B. dothidea, which provides a theoretical basis for the development of target-based fungicides.