青枯菌GMI1000效应蛋白RipQ对致病力的作用研究  

The role of effector RipQ for virulence in Ralstonia solanacearum GMI1000

作　　者：贵彩英 TAHIRA Saleem 谢文松 卓涛[1] 户勋[1] 邹华松[1] 范晓静[1] GUI Caiying;TAHIRA Saleem;XIE Wensong;ZHUO Tao;HU Xun;ZOU Huasong;FAN Xiaojing(College of Plant Protection,Fujian Agriculture and Forestry University,Fuzhou 350002,China)

机构地区：[1]福建农林大学植物保护学院,福州350002

出　　处：《植物病理学报》2022年第5期801-812,共12页Acta Phytopathologica Sinica

基　　金：国家自然科学基金(31801696,31872919);福建省自然科学基金(2019J01372);福建农林大学科技创新专项基金(CXZX2019015G)。

摘　　要：青枯菌通过Ⅲ型分泌系统向寄主植物细胞分泌100多种效应蛋白,对寄主植物的抗感病性产生影响。青枯菌效应蛋白RipQ启动子区存在典型的HrpB识别序列PIP box(5′-TTCGG-N15-TTCGC-3′),但其功能尚未明确。本研究分析了RipQ在青枯菌4种演化型菌株中的分布情况。以青枯菌GMI1000为出发菌,构建ripQ缺失突变体和过表达菌株,研究效应蛋白RipQ在青枯菌-番茄植物互作中的功能。结果显示,ripQ广泛分布于除演化型IV的不同青枯菌类群中。与野生型菌株相比,ripQ突变体在番茄上的致病力有一定程度的增强,而ripQ过表达菌株的致病力显著降低。突变体和过表达菌株在培养基中的生长与野生型没有区别,但过表达菌株在番茄体内的繁殖能力下降。RipQ过表达菌株侵染番茄后hrpB、hrpG和epsA基因表达量显著下调,且能够诱导番茄叶片H_(2)O_(2)的大量累积,过敏性坏死反应标志基因hin1和水杨酸信号通路标志基因PR1a的诱导表达。另外,在番茄上瞬时表达ripQ也可以观察到H_(2)O_(2)积累及叶片细胞坏死,伴随着hin1和PR1a的上调表达。这些结果表明效应蛋白RipQ具有诱导番茄抗性的作用,从而影响青枯菌在番茄植物上的致病力。Ralstonia solanacearum injects over 100 effector proteins into host cells by the typeⅢsecretion system,which modulate host defense and susceptibility responses.The effector protein RipQ contains a typical plant-inducible promoter(PIP)box motif(consensus 5′-TTCGG-N15-TTCGC-3′)on the putative promoter region,a recognition sequence by the HrpB transcriptional activator,and yet its function remains unclear in R.solanacearum.In this study,we analyzed the distribution of ripQ gene in R.solanacearum species complex.To study the function of ripQ in R.solanacearum-tomato interaction,ripQ deletion mutantΔripQ and over-expression strain GMI1000::ripQ were constructed in GMI1000.The results showed that the ripQ gene is widely distributed in various phylotypes of R.solanacearum except for phylotype IV.In contrast to wild type GMI1000,the mutantΔripQ showed mild enhanced virulence on tomato plants,whereas the virulence of GMI1000::ripQ was significantly reduced.The growth ofΔripQ and GMI1000::ripQ showed no difference from that of the wild type cultured in liquid medium,but GMI1000::ripQ replicated much slower than the wild type in tomato plant.The expression levels of pathogenic genes hrpB,hrpG and epsA were downregulated after infection tomato with GMI1000::ripQ,accompanied by the induced an accelerated accumulation of H_(2)O_(2),and the higher expression of hypersensitive response marker gene hin1 and SA signaling marker gene PR1a.Furthermore,transient expression of ripQ in tomato leaves resulted in induced H_(2)O_(2) accumulation,cell death,hin1 and PR1a high levels expression.These results indicated that effector RipQ exerted a role in the induction of host defense,thereby influencing the virulence of R.solanacearum on tomato plants.

关 键 词：青枯菌 效应蛋白RipQ 抗性 致病力 

分 类 号：S432.42[农业科学—植物病理学]