title: The Fus3/Kss1 MAP kinase homolog Amk1 regulates the expression of genes encoding hydrolytic enzymes in Alternaria brassicicola.
abstract: Mitogen-activated protein (MAP) kinases have been shown to be required for virulence in diverse phytopathogenic fungi. To study its role in pathogenicity, we disrupted the Amk1 MAP kinase gene, a homolog of the Fus3/Kss1 MAP kinases in Saccharomyces cerevisiae, in the necrotrophic Brassica pathogen, Alternaria brassicicola. The amk1 disruption mutants showed null pathogenicity on intact host plants. However, amk1 mutants were able to colonize host plants when they were inoculated on a physically damaged host surface, or when they were inoculated along with nutrient supplements. On intact plants, mutants expressed extremely low amounts of several hydrolytic enzyme genes that were induced over 10-fold in the wild-type during infection. These genes were also dramatically induced in the mutants on wounded plants. These results imply a correlation between virulence and the expression level of specific hydrolytic enzyme genes plus the presence of an unidentified pathway controlling these genes in addition to or in conjunction with the Amk1 pathway.
authors.affiliation: Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
authors.forename: Yangrae
authors.initials: Y
authors.lastname: Cho
authors.forename: Robert A
authors.initials: RA
authors.lastname: Cramer
authors.forename: Kwang-Hyung
authors.initials: KH
authors.lastname: Kim
authors.forename: Josh
authors.initials: J
authors.lastname: Davis
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Mitchell
authors.forename: Patricia
authors.initials: P
authors.lastname: Figuli
authors.forename: Barry M
authors.initials: BM
authors.lastname: Pryor
authors.forename: Emily
authors.initials: E
authors.lastname: Lemasters
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Lawrence
mesh_terms: D000528:Alternaria / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity*; D001937:Brassica / Q000382:microbiology*; D015966:Gene Expression Regulation, Fungal; D006867:Hydrolases / Q000235:genetics*; D006868:Hydrolysis; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology*; D014774:Virulence / Q000235:genetics
chemical_list: D020928:Mitogen-Activated Protein Kinases; D006867:Hydrolases