The high-osmolarity glycerol pathway plays an important role in the responses of fungi to various environmental stresses. Saccharomyces cerevisiae Skn7 is a response regulator in the high-osmolarity glycerol pathway, which regulates the oxidative stress response, cell cycle and cell wall biosynthesis. In this study, we characterized an Skn7 orthologue BcSkn7 in Botrytis cinerea. BcSKN7 can partly restore the growth defects of S. cerevisiae SKN7 mutant and vice versa. The BcSKN7 mutant (ΔBcSkn7-1) revealed increased sensitivity to ionic osmotic and oxidative stresses and to ergosterol biosynthesis inhibitors. In addition, ΔBcSkn7-1 was also impaired dramatically in conidiation and sclerotial formation. Western blot analysis showed that BcSkn7 positively regulated the phosphorylation of BcSak1 (the orthologue of S. cerevisiae Hog1) under osmotic stress, indicating that BcSkn7 is associated with the high-osmolarity glycerol pathway in B. cinerea. In contrast with BcSak1, BcSkn7 is not involved in the regulation of B. cinerea virulence. All of the phenotypic defects of ΔBcSkn7-1 are restored by genetic complementation of the mutant with the wild-type BcSKN7. The results of this study indicate that BcSkn7 plays an important role in the regulation of vegetative differentiation and in the response to various stresses in B. cinerea.

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B. cinerea group S isolates are widespread in all strawberry-growing locations in Zhejiang Province. The natural HydR populations from strawberry are dominated by B. cinerea group S. © 2015 Society of Chemical Industry.

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