Survival factor 1 contributes to growth development, oxidative stress response, patulin production and virulence in Penicillium expansum

Penicillium expansum causes blue mold disease and produces toxic patulin on postharvest fruits, resulting in serious economic loss and food concerns. Reactive oxygen species (ROS) is critical in determining the virulence of P. expansum, and survival factor 1 (Svf1) is identified to promote yeast survival under oxidative stress conditions. However, whether Svf1 is involved in the pathogenicity of P. expansum remains unclear. In this study, a putative Pesvf1 gene was identified in P. expansum and the ΔPesvf1 mutant was constructed by homologous recombination to analyze ROS production, patulin accumulation and its pathogenicity on apple fruit. The deletion strain ΔPesvf1 showed defective hyphal growth with excessive lateral branching, reduced patulin production by down-regulating its biosynthetic genes, and increased sensitivity to oxidative stress that induced endogenous ROS production. Additionally, lipidomics reveals lipid metabolism remodeling when loss of PeSvf1, including accumulated triacylglycerol (TAG), phosphatidylcholines (PCs), sphingomyelins (SMs) and phosphatidylethanolamines (PEs), that resulting in generation of lipid droplets (LDs) and affecting both the cell membrane integrity and cell permeability. Furthermore, ΔPesvf1 strain exhibited attenuated virulence on Fuji apples. Collectively, our results provided new insights into the mechanisms through which PeSvf1 regulates the growth development, oxidative stress response, lipid metabolism, patulin production and virulence of P. expansum, suggesting a potential of PeSvf1 to be a target of developing safe antifungal substrate to control blue mold in postharvest fruits.