The two-component histidine kinase BdHk1 regulates fungal development, virulence and fungicide sensitivity in Botryosphaeria dothidea

Histidine kinases (HKs) allow fungal cells to sense and respond to environmental stimuli. However, the biological role of HKs in Botryosphaeria dothidea, the causal agent of Botryosphaeria canker and apple ring rot, remains unknown. In this study, we identified and characterized the two-component histidine kinase BdHk1 in B. dothidea. Targeted knockout of BdHK1 gene resulted in severe conidiation and pathogenicity defects. In addition, the ΔBdHk1 mutant showed hypersensitivity to osmotic stress, but resistance to phenylpyrrole and dicarboximide fungicides. Moreover, the ΔBdHk1 mutant exhibited significantly increased sensitivity to the cell membrane-damaging agent SDS and high temperature. Comparative transcriptome analysis revealed that inactivation of BdHk1 influenced multiple metabolic pathways in B. dothidea. Taken together, our results suggest that BdHk1 plays an important role in development, virulence and stress tolerance in B. dothidea.