hrp基因关键调控因子HrpG在水稻白叶枯病菌和条斑病菌中的交叉互补性研究  

HrpG,a major regulator of hrp genes,is interchangeable between Xanthomonas oryzae pv.oryzae and pv.oryzicola

作　　者：熊鹂[1] 刘之洋[1] 邹华松[1] 邹丽芳[1] 陈功友[1] 

机构地区：[1]上海交通大学农业与生物学院,上海200240

出　　处：《植物病理学报》2014年第4期405-413,共9页Acta Phytopathologica Sinica

基　　金：国家自然科学基金资助项目(31000071);第43批"留学回国人员科研启动基金"项目

摘　　要：水稻自叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)和条斑病菌(X.oryzae pv.oryzicola,Xoc)在非寄主烟草上产生过敏反应(HR)和在寄主水稻上具有致病性,是由hrp致病岛决定的,其中HrppG为关键调控因子。Xoo和Xoc侵染水稻途径和在水稻上产生病害症状的不同,是否与hrpG基因有关,还不清楚。本研究利用反向遗传学方法获得了Xoo和Xoc的hrpG突变体:P△hrpG和R△hrpG,并用hrpG_(Xoo)基因和hrpG_(Xoc)基因分别互补上述2个突变体,获得了相应的互补菌株。致病性测定结果显示,P△hrpG和R△hrpG突变体丧失了在水稻上的致病性和在非寄主烟草上产生HR的能力,而hrpG_(Xoo)基因和hrpG_(Xoc)基因可分别互补上述突变体至野生型水平。利用GUS报告基因检测基因启动子活性发现,hrpG_(Xoo)和hrpG_(Xoc)的启动子活性没有显著差别;RT-PCR和Western杂交结果显示,hrpG基因交叉互补菌株中HrpG调控的下游基因hrpX、hpaR、hrcT、hpa2和hrpD6的表达没有差异,且Ⅲ型分泌系统分泌蛋白Hpa2的分泌性没有受到影响。这些结果表明,稻黄单胞菌hrpG基因可在Xoo和Xoc中交叉互置,位于其上游和下游的调控途径可能相似,而决定Xoo和Xoc在水稻上的侵染途径以及所致病害症状差异可能与hrpG基因位点无关。Hypersensitive on nonhost tobacco and pathogenicity on host rice caused by Xanthomonas oryzae pv. oryzae （Xoo） and X. oryzae pv. oryzicola （Xoc） are dependent on hrp pathogenicity island, in which HrpG is a major regulator. It is still unclear that whether the hrpG gene is related to the different infection approaches and symptoms caused by Xoo and Xoc on the rice leaf. In this study, we constructed Xoo hrpG mutant PAhrpG and Xoc hrpG mutant RAhrpG by a reverse genetic approach respectively, and complementary strains of PAhrpG and RAhrpG by hrpGxoo and hrpGxoc, were obtained respectively. The GUS activity assay showed that there was no obvious difference in promoter activity between the hrpGxoo and hrpGxoc genes. The RT-PCR results showed that the expressions of hrpX, hpaR, hrcT, hpa2 and hrpD6, the downstream genes of hrpG in the hrpG cross-complemented strains, were not changed when compared to their wild type strains. In addition, the Western blot assay showed that secretion of Hpa2 through type Ⅲ secretion system was not affected. These evidences indicate that the hrpG genes are interchangeable between Xoo and Xoc, and the upstream or downstream regulatory pathway might be similar. However, the hrpG gene isn＇t responsible for differences of infection approaches and symptoms in rice leaf caused by Xoo and Xoc.

关 键 词：水稻白叶枯病菌 水稻条斑病菌 hrpG基因 功能互补 致病性 

分 类 号：S435.111.47[农业科学—农业昆虫与害虫防治] S435.111.49[农业科学—植物保护]