MAPKs and acetyI-CoA are associated with Curvularia lunata pathogenicity and toxin production in maize

Mitogen-activated protein kinase （MAPK） cascades play an important role in extracellular signal transduction and are involved in the pathogenicity of fungal pathogens to host plants. In Curvularia lunata, the roles of two MAPK genes, Clkl and CIm 1, have already been studied. Clkl is involved in conidia formation and pathogenicity, and Clmf is closely related to pathogen cell wall formation and pathogenicity to maize leaves. In this study, a third C. lunata MAPK gene, Clhl, which is homologous to hog1, was successfully cloned. We found that a Clhl deletion mutant had lower intracellular glycerol accumulation than the wild-type stain and was unable to grow normally under osmotic stress conditions. Furthermore, the deletion mutants of three C. lunata MAPK genes （Clkl, Clml and Clhl） had lower levels of acetyI-CoA, which is an important intermediate product in the synthesis of melanin and furan toxin, and down-regulated expression of pathogenicity-associated genes. Furthermore, pathogenicity and the ability to produce toxin were restored after adding acetyI-CoA to the culture medium, suggesting that acetyI-CoA is closely involved in the pathogen MAPK signaling pathway.