title: Identification, cloning, and characterization of PWL2, a gene for host species specificity in the rice blast fungus.
abstract: Genetic analysis of host specificity in the rice blast fungus (Magnaporthe grisea) identified a single gene, PWL2 (for Pathogenicity toward Weeping Lovegrass), that exerts a major effect on the ability of this fungus to infect weeping lovegrass (Eragrostis curvula). The allele of the PWL2 gene conferring nonpathogenicity was genetically unstable, with the frequent appearance of spontaneous pathogenic mutants. PWL2 was cloned based on its map position. Large deletions detected in pathogenic mutants guided the gene cloning efforts. Transformants harboring the cloned PWL2 gene lost pathogenicity toward weeping lovegrass but remained fully pathogenic toward other host plants. Thus, the PWL2 host species specificity gene has properties analogous to classical avirulence genes, which function to prevent infection of certain cultivars of a particular host species. The PWL2 gene encodes a glycine-rich, hydrophilic protein (16 kD) with a putative secretion signal sequence. The pathogenic allele segregating in the mapping population, pwl2-2, differed from PWL2 by a single base pair substitution that resulted in a loss of function. The PWL2 locus is highly polymorphic among rice pathogens from diverse geographic locations.
authors.affiliation: DuPont Central Research and Development, E. I. du Pont de Nemours and Company, Wilmington, Delaware 19880-0402, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Sweigard
authors.forename: A M
authors.initials: AM
authors.lastname: Carroll
authors.forename: S
authors.initials: S
authors.lastname: Kang
authors.forename: L
authors.initials: L
authors.lastname: Farrall
authors.forename: F G
authors.initials: FG
authors.lastname: Chumley
authors.forename: B
authors.initials: B
authors.lastname: Valent
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001203:Ascomycota / Q000235:genetics* / Q000472:pathogenicity; D001483:Base Sequence; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D018076:DNA, Complementary / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal / Q000235:genetics*; D005843:Geography; D008540:Meiosis; D008969:Molecular Sequence Data; D016296:Mutagenesis; D012275:Oryza / Q000382:microbiology; D010935:Plant Diseases / Q000235:genetics*; D010944:Plants / Q000382:microbiology*; D013045:Species Specificity; D014774:Virulence / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D005656:Fungal Proteins; C095732:PWL2 protein, Magnaporthe grisea