A putative polyketide synthase/peptide synthetase from Magnaporthe grisea signals pathogen attack to resistant rice.
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.
FRE 2579 Centre National de la Recherche Scientifique/Bayer CropScience, F-69263 Lyon Cedex 09, France.
Heidi U
HU
Böhnert
Isabelle
I
Fudal
Waly
W
Dioh
Didier
D
Tharreau
Jean-Loup
JL
Notteghem
Marc-Henri
MH
Lebrun
D000595:Amino Acid Sequence / Q000235:genetics; D001483:Base Sequence / Q000235:genetics; D003593:Cytoplasm / Q000201:enzymology / Q000235:genetics; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics*; D046911:Macromolecular Substances; D020082:Magnaporthe / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D010453:Peptide Synthases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D048630:Polyketide Synthases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics
D018076:DNA, Complementary; D005656:Fungal Proteins; D046911:Macromolecular Substances; D011993:Recombinant Fusion Proteins; D048630:Polyketide Synthases; D010453:Peptide Synthases