title: The mitogen-activated protein kinase gene MAF1 is essential for the early differentiation phase of appressorium formation in Colletotrichum lagenarium.
abstract: Colletotrichum lagenarium, the causal agent of cucumber anthracnose, invades host plants by forming a specialized infection structure called an appressorium. In this fungus, the mitogen-activated protein kinase (MAPK) gene CMK1 is involved in several steps of the infection process, including appressorium formation. In this study, the goal was to investigate roles of other MAPKs in C. lagenarium. The MAPK gene MAF1, related to Saccharomyces cerevisiae MPK1 and Magnaporthe grisea MPS1, was isolated and functionally characterized. The maf1 gene replacement mutants grew normally, but there was a significant reduction in conidiation and fungal pathogenicity. The M. grisea mps1 mutant forms appressoria, but conidia of the C. lagenarium maf1 mutants produced elongated germ tubes without appressoria on both host plant and glass, on which the wild type forms appressoria, suggesting that MAF1 has an essential role in appressorium formation on inductive surfaces. On a nutrient agar, wild-type conidia produced elongated germ tubes without appressoria. The morphological phenotype of the wild type on the nutrient agar was similar to that of the maf1 mutants on inductive surfaces, suggesting repression of the MAF1-mediated appressorium differentiation on the nutrient agar. The cmk1 mutants failed to form normal appressoria but produced swollen, appressorium-like structures on inductive surfaces, which is morphologically different from the maf1 mutants. These findings suggest that MAF1 is required for the early differentiation phase of appressorium formation, whereas CMK1 is involved in the maturation of appressoria.
authors.affiliation: Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Kaihei
authors.initials: K
authors.lastname: Kojima
authors.forename: Taisei
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Takano
authors.forename: Eriko
authors.initials: E
authors.lastname: Oshiro
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Okuno
mesh_terms: D000595:Amino Acid Sequence; D020231:Colletotrichum / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity; D018553:Cucumis sativus / Q000382:microbiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D056229:Fungal Structures / Q000235:genetics / Q000254:growth & development*; D020043:Genes, Essential / Q000235:genetics; D020082:Magnaporthe / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; C072724:SLT2 protein, S cerevisiae; C409987:cmk1 protein, Colletotrichum lagenarium; C093416:MPS1 protein, S cerevisiae