The MAPKKK CgMck1 Is Required for Cell Wall Integrity, Appressorium Development, and Pathogenicity in Colletotrichum gloeosporioides

Abstract

Mitogen-activated protein kinase (MAPK) signaling pathway plays key roles in sensing extracellular signals and transmitting them from the cell membrane to the nucleus in response to various environmental stimuli. A MAPKKK protein CgMck1 in <i>Colletotrichum gloeosporioides</i> was characterized. Phenotypic analyses of the ∆<i>Cgmck1</i> mutant showed that the CgMck1 was required for vegetative growth, fruiting body development, and sporulation. Additionally, the <i>CgMCK1</i> deletion mutant showed significant defects in cell wall integrity, and responses to osmotic stresses. The mutant abolished the ability to develop appressorium, and lost pathogenicity to host plants. The ∆<i>Cgmck1</i> mutant also exhibited a higher sensitivity to antifungal bacterium agent <i>Bacillus velezensis</i>. The deletion mutants of downstream MAPK cascades components CgMkk1 and CgMps1 showed similar defects to the ∆<i>Cgmck1</i> mutant. In conclusion, CgMck1 is involved in the regulation of vegetative growth, asexual development, cell wall integrity, stresses resistance, and infection morphogenesis in <i>C. gloeosporioides</i>.