The Sensor Proteins BcSho1 and BcSln1 Are Involved in, Though Not Essential to, Vegetative Differentiation, Pathogenicity and Osmotic Stress Tolerance in .

High-osmolarity glycerol (HOG) signaling pathway belongs to mitogen-activated protein kinase (MAPK) cascades that regulate responses of organism to diverse extracellular stimuli. The membrane spanning proteins Sho1 and Sln1 serve as biosensors of HOG pathway in . In this study, we investigated the biological functions of and in the gray mold fungus . Target gene deletion demonstrated that both and are important for mycelial growth, conidiation and sclerotial formation. The and double deletion mutant Δ produced much more, but smaller sclerotia than Δ and the wild-type (WT) strain, while Δ failed to develop sclerotia on all tested media, instead, formed a large number of conidia. Infection tests revealed that the virulence of Δ decreased significantly, however, Δ or Δ showed no difference with the WT strain. In addition, Δ exhibited resistance to osmotic stress by negatively regulating the phosphorylation of BcSak1 (yeast Hog1). All the phenotypic defects of mutants were recovered by target gene complementation. These results suggest that and share some functional redundancy in the regulation of fungal development, pathogenesis and osmotic stress response in .