putative polyketide synthase/peptide synthetase from Magnaporthe grisea signals pathogen attack to resistant rice

• Published in: The Plant cell Vol. 16; no. 9; pp. 2499 - 2513
• Main Authors: Bohnert, H.U, Fudal, I, Dioh, W, Tharreau, D, Notteghem, J.L, Lebrun, M.H
• Format: Journal Article
• Language: English
• Published: England American Society of Plant Biologists 01-09-2004
• Subjects: ACE1 gene; Amino Acid Sequence - genetics; appressoria; Barley; Base Sequence - genetics; Biosynthesis; blast disease; Cloning; Cultivars; Cytoplasm - enzymology; Cytoplasm - genetics; DNA, Complementary - analysis; DNA, Complementary - genetics; Enzymes; Fungal Proteins - genetics; Fungal Proteins - isolation & purification; Fungal Proteins - metabolism; gene expression; Gene Expression Regulation, Fungal - genetics; Genes; Genomes; Genomics; host-pathogen relationships; Immunity, Innate - genetics; Introns; leaves; Macromolecular Substances; Magnaporthe - enzymology; Magnaporthe - genetics; Magnaporthe grisea; Metabolites; Molecular Sequence Data; nucleotide sequences; Oryza - enzymology; Oryza - genetics; Oryza - microbiology; Oryza sativa; pathogenicity; Pathogens; Peptide Synthases - genetics; Peptide Synthases - isolation & purification; Peptide Synthases - metabolism; peptide synthetase; Phylogeny; Plant Diseases - genetics; Plant Leaves - enzymology; Plant Leaves - genetics; plant pathogenic fungi; polyketide synthase; Polyketide Synthases - genetics; Polyketide Synthases - isolation & purification; Polyketide Synthases - metabolism; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Reverse transcriptase polymerase chain reaction; Rice; Signal Transduction - genetics
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.104.022715

Isolates of the rice blast fungus Magnaporthe grisea that carry the gene encoding Avirulence Conferring Enzyme1 (ACE1) are specifically recognized by rice (Oryza sativa) cultivars carrying the resistance gene Pi33. This recognition enables resistant plants to activate a defense response. ACE1 was isolated by map-based cloning and encodes a putative hybrid between a polyketide synthase and a nonribosomal peptide synthetase, enzymes involved in microbial secondary metabolism. ACE1 is expressed exclusively during fungal penetration of host leaves, the time point at which plant defense reactions are triggered. Ace1 appears to be localized in the cytoplasm of the appressorium. Mutation of the putative catalytic site of the beta-ketoacyl synthase domain of Ace1 abolishes recognition of the fungus by resistant rice. This suggests that Ace1 biosynthetic activity is required for avirulence. Our results are consistent with the hypothesis that the fungal signal recognized by resistant rice plants is the secondary metabolite whose synthesis depends on Ace1.