中国水稻白叶枯病菌小种C8菌株无毒基因的分离及功能鉴别  

Identification of a Specific Avirulence Gene from a Chinese Race C8 of Xanthomonas oryzae pv.oryzae

作　　者：纪志远[1] 杨娟[1] 王寅鹏[1] 周丹[1] 李玉蓉[1] 邹丽芳[2] 陈功友[1,2] 

机构地区：[1]南京农业大学植物保护学院/农业部病虫监测与治理重点开放实验室,江苏南京210095 [2]上海交通大学农业与生物学院,上海200240

出　　处：《中国水稻科学》2009年第5期463-469,共7页Chinese Journal of Rice Science

基　　金：国家自然科学基金资助项目(30710103902;30671354);国家863计划资助项目(2006AA02Z180);公益性行业(农业)科研专项经费资助项目(NYHYZX07-056)

摘　　要：白叶枯病菌与水稻间的互作符合基因对基因模式,不同小种中存在特异的avrBs3/pthA家族基因。对中国水稻白叶枯病菌小种C8菌株基因组DNA进行BamHⅠ酶切和Southern杂交,发现了其特有的约6.0 kb大小、含avrBs3/pthA家族基因的信号条带。经文库筛选、Southern杂交和限制性酶切分析,获得了C8小种avr/pthC8 a基因。将该基因导入菲律宾小种6的代表菌株PXO99A中,发现avr/pthC8 a可使PXO99A丧失对水稻品种Asominori(携有成株期抗性基因Xa17)的毒性,暗示avr/pthC8 a可能是与Xa17相应的无毒基因。序列分析发现,avr/pthC8 a基因大小为3816 bp,编码1272个氨基酸,由102 bp编码的34个氨基酸重复单元在基因内的重复数为20.5个,其3′端的BamHⅠ酶切位点由GGATCC突变为AGATCC,其他特征均与avrBs3/pthA家族的成员相似,即C端存在1个亮氨酸拉链、3个核定位信号和1个酸性转录激活域。avr/pthC8 a基因3′端的BamHⅠ酶切位点发生突变在avrBs3/pthA家族基因中鲜有报道。中国C8小种avr/pthC8 a基因的发掘,为进一步了解水稻黄单胞菌毒性变异以及avrBs3/pthA家族基因的进化提供了理论依据。The interaction between Xanthomonas oryzae pv. oryzae （Xoo） and rice follows gene-for-gene model. A 6.0 kb particular fragment was identified from a Chinese race C8 strain of Xoo, through screening its genomic library by Southern blot with a highly conserved EcoR J -BamH I fragment of the avrBs3/pthA family as probe. This specific DNA contained an avirulence gene, namely avr/pthC8a, which transmitted the Philippine strain PXO99A from compatible into incompatible interactions with rice Asominori carrying R gene Xa17, suggesting that avr/pthC8a is possibiy corresponding for Xa17 specificity. Sequence analysis showed that avr/pthC8a, 3819 bp in size, is a avrBs3/pthA family member, and the repeat number of the I02 bp repeat unit is 20.5. The structure of the gene is almost as same as those of the avrBs3/pthA family genes at 5＇ and 3＇-terminals. The putative protein has a lucine zipper, three nucleotide location signals and an acid transcriptional activation domain at C-terminal. The novel is that the BarnH I site at 3＇-terminal of the gene is mutagenesis from GGATCC into AGATCC, which has not been reported so far. Thus, identification of avr/pthC8a of Chinese race C8 provides a fundamental understanding of virulence differentiation among different races of Xoo and coevolution of avrBs3/pthA genes with rice.

关 键 词：水稻 白叶枯病菌 无毒基因 基因功能 

分 类 号：S435.111.4[农业科学—农业昆虫与害虫防治]