Putative transcription factor Skn7 is involved in cell wall formation, oxidative stress response, and hydrophobin gene expression in Pleurotus ostreatus

The functions of the transcription factor Skn7 in regulating cell wall synthesis and oxidative stress response have been investigated in ascomycetes and a few basidiomycetes. We identified and disrupted the putative skn7 gene in Pleurotus ostreatus, a basidiomycete. The Δskn7 strains exhibited a 37% decrease in cell wall thickness despite unchanged cell wall polysaccharide composition. Notably, alongside the reduced expression of eight of the 12 cell wall synthase genes, a 66.1% decrease in hydrophobin hydph16 expression was observed, potentially contributing to the thinner cell wall. Increased resistance to H2O2 was observed in the Δskn7 strains, despite decreased expression of two of the seven antioxidant genes. The mechanism underlying this unexpected phenotype remains unclear; however, the potential involvement of the highly expressed hydrophobin vmh3 is of interest. Skn7 may play a role in cell-wall structure formation and oxidative stress resistance by regulating the expression of hydrophobin genes in the fungus.