title: Two novel fungal virulence genes specifically expressed in appressoria of the rice blast fungus.
abstract: The PMK1 mitogen-activated protein kinase gene regulates appressorium formation and infectious hyphae growth in the rice blast fungus. To further characterize this mitogen-activated protein kinase pathway, we constructed a subtraction library enriched for genes regulated by PMK1. Two genes identified in this library, GAS1 and GAS2, encode small proteins that are homologous with gEgh16 of the powdery mildew fungus. Both were expressed specifically during appressorium formation in the wild-type strains, but neither was expressed in the pmk1 mutant. Mutants deleted in GAS1 and GAS2 had no defect in vegetative growth, conidiation, or appressoria formation, but they were reduced in appressorial penetration and lesion development. Interestingly, deletion of both GAS1 and GAS2 did not have an additive effect on appressorial penetration and lesion formation. The GAS1-green fluorescent protein and GAS2-green fluorescent protein fusion proteins were expressed only in appressoria and localized in the cytoplasm. These two genes may belong to a class of proteins specific for filamentous fungi and function as novel virulence factors in fungal pathogens.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Xue
authors.forename: Gyungsoon
authors.initials: G
authors.lastname: Park
authors.forename: Woobong
authors.initials: W
authors.lastname: Choi
authors.forename: Li
authors.initials: L
authors.lastname: Zheng
authors.forename: Ralph A
authors.initials: RA
authors.lastname: Dean
authors.forename: Jin-Rong
authors.initials: JR
authors.lastname: Xu
mesh_terms: D000595:Amino Acid Sequence; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D056229:Fungal Structures / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D001467:Hordeum / Q000382:microbiology; D020082:Magnaporthe / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000382:microbiology*; D010641:Phenotype; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014774:Virulence / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D020928:Mitogen-Activated Protein Kinases; C102726:Pmk1 protein, Magnaporthe grisea