R gene expression induced by a type-III effector triggers disease resistance in rice.
Disease resistance (R) genes in plants encode products that specifically recognise incompatible pathogens and trigger a cascade of events leading to disease resistance in the host plant. R-gene specificity is dictated by both host R genes and cognate avirulence (avr) genes in pathogens. However, the basis of gene-for-gene specificity is not well understood. Here, we report the cloning of the R gene Xa27 from rice and the cognate avr gene avrXa27 from Xanthomonas oryzae pv. oryzae. Resistant and susceptible alleles of Xa27 encode identical proteins. However, expression of only the resistant allele occurs when a rice plant is challenged by bacteria harbouring avrXa27, whose product is a nuclear localized type-III effector. Induction of Xa27 occurs only in the immediate vicinity of infected tissue, whereas ectopic expression of Xa27 resulted in resistance to otherwise compatible strains of the pathogen. Thus Xa27 specificity towards incompatible pathogens involves the differential expression of the R gene in the presence of the AvrXa27 effector.
Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604, Singapore.
Keyu
K
Gu
Bing
B
Yang
Dongsheng
D
Tian
Lifang
L
Wu
Dongjiang
D
Wang
Chellamma
C
Sreekala
Fan
F
Yang
Zhaoqing
Z
Chu
Guo-Liang
GL
Wang
Frank F
FF
White
Zhongchao
Z
Yin
D000483:Alleles; D001483:Base Sequence; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics*; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics* / Q000382:microbiology*; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology*; D013379:Substrate Specificity; D014774:Virulence / Q000235:genetics; D014974:Xanthomonas / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology