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

Plant Cell. 2004 Sep;16(9):2499-513. doi: 10.1105/tpc.104.022715. Epub 2004 Aug 19.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence / genetics
  • Base Sequence / genetics
  • Cytoplasm / enzymology
  • Cytoplasm / genetics
  • DNA, Complementary / analysis
  • DNA, Complementary / genetics
  • Fungal Proteins / genetics
  • Fungal Proteins / isolation & purification
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Fungal / genetics
  • Immunity, Innate / genetics*
  • Macromolecular Substances
  • Magnaporthe / enzymology*
  • Magnaporthe / genetics
  • Molecular Sequence Data
  • Oryza / enzymology*
  • Oryza / genetics
  • Oryza / microbiology
  • Peptide Synthases / genetics
  • Peptide Synthases / isolation & purification
  • Peptide Synthases / metabolism*
  • Phylogeny
  • Plant Diseases / genetics
  • Plant Leaves / enzymology
  • Plant Leaves / genetics
  • Polyketide Synthases / genetics
  • Polyketide Synthases / isolation & purification
  • Polyketide Synthases / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction / genetics

Substances

  • DNA, Complementary
  • Fungal Proteins
  • Macromolecular Substances
  • Recombinant Fusion Proteins
  • Polyketide Synthases
  • Peptide Synthases

Associated data

  • GENBANK/AJ704622
  • GENBANK/AJ704623
  • GENBANK/BN000505
  • GENBANK/BN000506
  • GENBANK/BN000507