Cloning and expression of three protein kinase genes of Colletotrichum gloeosporioides f. sp. Malvae
C. gloeosporioides f. sp. malvae (C.g.m.) is a hemibiotrophic pathogen of round-leaved mallow. Three genes belonging to the GSK-3, SNF-1, and MAP kinase families were cloned from C.g.m. GSK-3 and SNF-1 kinase are the first homologs from these groups of protein kinases found in a filamentous fungus. Expression of these genes were relatively low and either fluctuated slightly or were constant in glucose and glycerol cultures. However, cggsk and cgsnf were highly expressed in the early stages of infection during appressorium formation and the development of large primary hyphae. In contrast, cgmap showed constitutive expression during infection, which is typical of MAP kinases. Based on expression studies and sequence homology to other protein kinases, CGGSK could be involved in morphogenesis of infection structures, CGSNF could be transmitting nutritional or environmental signals during infection structure formation, and CGMAP could be involved in maintaining basic cellular functions or regulating appressorium formation and penetration.