Identification of an avirulence gene,avrxa5,from the rice pathogen Xanthomonas oryzae pv.oryzae  

作　　者：ZOU HuaSong ZHAO WenXiang ZHANG XiFu HAN YangChun ZOU LiFang CHEN GongYou 

机构地区：[1]School of Agriculture and Biology,Shanghai Jiaotong University,Shanghai 200240,China [2]College of Plant Protection,Nanjing Agricultural University/Laboratory for Monitoring and Management for Plant Pests and Diseases,Chinese Ministry of Agriculture,Nanjing 210095,China [3]Department of Agronomy,Henan Vocation-Technical Teachers College,Xinxiang 453003,China

出　　处：《Science China(Life Sciences)》2010年第12期1440-1449,共10页中国科学(生命科学英文版)

基　　金：supported by the State Key Basic Research and Development Project of China (Grant No. 2006CB101902);the National Natural Science Foundation of China (Grant Nos. 30710103902 and 30671354);the Ministry of Agriculture of China (Grant No. NYHYZX07-056)

摘　　要：Xanthomonas oryzae pv.oryzae,the causal agent of bacterial blight in rice,interacts with rice plants in a gene-for-gene manner.The specificity of the interaction is dictated by avirulence(avr) genes in the pathogen and resistance(R) genes in the host.To date,no avr genes that correspond to recessive R genes have been isolated.We isolated an avrBs3/pthA family gene,avrxa5,from our previously isolated clone p58,which was originally from strain JXOIII.The avrxa5 gene converted the PXO99A strain from compatible to incompatible in rice cultivars containing the recessive xa5 gene,but not in those containing the dominant Xa5 gene.Sequencing indicated that avrxa5,which is highly similar to members of the avrBs3/pthA family,encodes a protein of 1238 amino acid residues with a conserved carboxy-terminal region containing three nuclear localization signals and a transcription activation domain.It has 19.5 34-amino-acid direct repeats,but the 13th amino acid is missing in the fifth and ninth repetitive units.Domain swapping of the repetitive regions between avrxa5 and avrXa7 changed the avirulence specificity of the genes in xa5 and Xa7 rice lines,respectively.This indicates that avrxa5 is distinct from previously characterized avrBs3/pthA members.The specificity of avrxa5 toward recessive xa5 in rice could help us better understand the molecular mechanisms of plant-pathogen specific interactions.Xanthomonas oryzae pv.oryzae,the causal agent of bacterial blight in rice,interacts with rice plants in a gene-for-gene manner.The specificity of the interaction is dictated by avirulence(avr) genes in the pathogen and resistance(R) genes in the host.To date,no avr genes that correspond to recessive R genes have been isolated.We isolated an avrBs3/pthA family gene,avrxa5,from our previously isolated clone p58,which was originally from strain JXOIII.The avrxa5 gene converted the PXO99A strain from compatible to incompatible in rice cultivars containing the recessive xa5 gene,but not in those containing the dominant Xa5 gene.Sequencing indicated that avrxa5,which is highly similar to members of the avrBs3/pthA family,encodes a protein of 1238 amino acid residues with a conserved carboxy-terminal region containing three nuclear localization signals and a transcription activation domain.It has 19.5 34-amino-acid direct repeats,but the 13th amino acid is missing in the fifth and ninth repetitive units.Domain swapping of the repetitive regions between avrxa5 and avrXa7 changed the avirulence specificity of the genes in xa5 and Xa7 rice lines,respectively.This indicates that avrxa5 is distinct from previously characterized avrBs3/pthA members.The specificity of avrxa5 toward recessive xa5 in rice could help us better understand the molecular mechanisms of plant-pathogen specific interactions.

关 键 词：rice bacterial blight Xanthomonas oryzae pv.oryzae avrxa5 AVIRULENCE recessive resistance 

分 类 号：S511[农业科学—作物学]