tA single amino acid difference distinguishes resistant and susceptible alleles of the rice blast resistance gene Pi-ta.
The rice blast resistance (R) gene Pi-ta mediates gene-for-gene resistance against strains of the fungus Magnaporthe grisea that express avirulent alleles of AVR-Pita. Using a map-based cloning strategy, we cloned Pi-ta, which is linked to the centromere of chromosome 12. Pi-ta encodes a predicted 928-amino acid cytoplasmic receptor with a centrally localized nucleotide binding site. A single-copy gene, Pi-ta shows low constitutive expression in both resistant and susceptible rice. Susceptible rice varieties contain pi-ta(-) alleles encoding predicted proteins that share a single amino acid difference relative to the Pi-ta resistance protein: serine instead of alanine at position 918. Transient expression in rice cells of a Pi-ta(+) R gene together with AVR-Pita(+) induces a resistance response. No resistance response is induced in transient assays that use a naturally occurring pi-ta(-) allele differing only by the serine at position 918. Rice varieties reported to have the linked Pi-ta(2) gene contain Pi-ta plus at least one other R gene, potentially explaining the broadened resistance spectrum of Pi-ta(2) relative to Pi-ta. Molecular cloning of the AVR-Pita and Pi-ta genes will aid in deployment of R genes for effective genetic control of rice blast disease.
Bryan
G T
GT
DuPont Agricultural Products, P.O. Box 80402, Wilmington, Delaware 19880-0402, USA.
Wu
K S
KS
Farrall
L
L
Jia
Y
Y
Hershey
H P
HP
McAdams
S A
SA
Faulk
K N
KN
Donaldson
G K
GK
Tarchini
R
R
Valent
B
B
D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D022202:Chromosomes, Artificial, Bacterial; D003001:Cloning, Molecular; D017931:DNA Primers; D008666:Metalloendopeptidases / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins
D017931:DNA Primers; D010940:Plant Proteins; C413573:AVP-Pita protein, Oryza sativa; D008666:Metalloendopeptidases