GTPase Rac Regulates Conidiation, AFB1 Production and Stress Response in Pathogenic Fungus

As a member of the Rho family, Rac plays important roles in many species, including proliferation, differentiation, apoptosis, DNA damage responses, metabolism, angiogenesis, and immunosuppression. In this study, by constructing -deleted mutants in , it was found that the deletion of gene led to the decline of growth and development, conidia production, AFB1 toxin synthesis, and seed infection ability of . The deletion of gene also caused the disappearance of sclerotium, indicating that is required for sclerotium formation in . The sensitivity of -deficient strains responding to cell wall stress and osmotic pressure stress increased when compared to WT. The Western blot result showed that mitogen-activated serine/threonine-protein kinase Slt2 and mitogen-activated protein kinase Hog1 proteins were no longer phosphorylated in -deficient strains of , showing that Rac may be used as a molecular switch to control the Slt2-MAPK cascade pathway and regulate the osmotic Hog-MAPK cascade pathway in in response to external stress. Altogether, these results indicated that Rac was involved in regulating the growth and development, conidia formation and AFB1 synthesis, and response to cell wall stress and osmotic pressure stress in .