Direct interaction of resistance gene and avirulence gene products confers rice blast resistance.
Rice expressing the Pi-ta gene is resistant to strains of the rice blast fungus, Magnaporthe grisea, expressing AVR-Pita in a gene-for-gene relationship. Pi-ta encodes a putative cytoplasmic receptor with a centrally localized nucleotide-binding site and leucine-rich domain (LRD) at the C-terminus. AVR-Pita is predicted to encode a metalloprotease with an N-terminal secretory signal and pro-protein sequences. AVR-Pita(176) lacks the secretory and pro-protein sequences. We report here that transient expression of AVR-Pita(176) inside plant cells results in a Pi-ta-dependent resistance response. AVR-Pita(176) protein is shown to bind specifically to the LRD of the Pi-ta protein, both in the yeast two-hybrid system and in an in vitro binding assay. Single amino acid substitutions in the Pi-ta LRD or in the AVR-Pita(176) protease motif that result in loss of resistance in the plant also disrupt the physical interaction, both in yeast and in vitro. These data suggest that the AVR-Pita(176) protein binds directly to the Pi-ta LRD region inside the plant cell to initiate a Pi-ta-mediated defense response.
Jia
Y
Y
DuPont Agricultural Products, PO Box 80402, Wilmington, DE 19880-0402, USA.
McAdams
S A
SA
Bryan
G T
GT
Hershey
H P
HP
Valent
B
B
D001665:Binding Sites; D019470:Biolistics; D018014:Gene Transfer Techniques; D005800:Genes, Fungal; D017343:Genes, Plant; D020082:Magnaporthe / Q000235:genetics* / Q000472:pathogenicity; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism; D012275:Oryza / Q000235:genetics*; D010935:Plant Diseases / Q000235:genetics*; D018515:Plant Leaves / Q000382:microbiology; D010940:Plant Proteins; D011485:Protein Binding; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
C413574:Pi-ta protein, Oryza sativa; D010940:Plant Proteins; D018160:Receptors, Cytoplasmic and Nuclear; C413573:AVP-Pita protein, Oryza sativa; D008666:Metalloendopeptidases