The FvHOG1 pathway is essential for stress responses, fungicide resistance, fumonisin B1 production and pathogenesis in Fusarium verticillioides.

The high-osmolarity glycerol (Hog) 1 signaling pathway is a component of mitogen-activated protein kinase (MAPK) cascades, which govern the responses of organisms to a wide variety of extracellular stimuli and assume a pivotal role in modulating growth, development, and pathogenicity across various organisms. However, the functions of Hog1-MAPK pathway proteins and the underlying mechanisms governing their development and pathogenicity remain largely unclear in Fusarium verticillioides. In this study, we investigated the role of all five Hog1-MAPK pathway genes (FvSln1, FvSho1, FvSsk2, FvPbs2 and FvHog1) in F. verticillioides. Target gene deletion demonstrated that FvSln1 and FvSho1 play a minor role in the response to osmotic stress, but the virulence of ΔFvSho1 in maize is impaired. The FvSsk2, FvPbs2 and FvHog1 mutants all presented a reduction in conidiation. These mutants are not only hypersensitive to osmotic stress but also show increased tolerance to oxidative stress, plasma membrane stress, and cell wall stress. The FvSsk2, FvPbs2 and FvHog1 mutants led to impairments in FB1 biosynthesis and pathogenicity. Interestingly, these mutants also have increased tolerance to fungicides. Overall, the findings of our study suggest that the FvSsk2-FvPbs2-FvHog1 MAPK cascade plays a crucial role in modulating conidiation, FB1 production, plant infection, and responses to hyperosmotic and general stresses in F. verticillioides.