猕猴桃溃疡病菌不致病菌株G230的鉴定及形成原因分析  

Determining the molecular basis for the loss-of-virulence in bacterial pathogen Pseudomonas syringae pv.actinidiae isolate G230

作　　者：谢婷 吴石平[2] 张清华 王紫颖 莫祥恺 杨再福[1] 赵志博 黄丽丽[3] Xie Ting;Wu Shiping;Zhang Qinghua;Wang Ziying;Mo Xiangkai;Yang Zaifu;Zhao Zhibo;Huang Lili(College of Agriculture,Guizhou University,Guiyang 550025,Guizhou Province,China;Institute of Plant Protection,Guizhou Academy of Agricultural Sciences,Guiyang 550006,Guizhou Province,China;College of Plant Protection,Northwest A&F University,Yangling 712100,Shaanxi Province,China)

机构地区：[1]贵州大学农学院,贵阳550025 [2]贵州省农业科学院植物保护研究所,贵阳550006 [3]西北农林科技大学植物保护学院,杨凌712100

出　　处：《植物保护学报》2023年第4期932-944,共13页Journal of Plant Protection

基　　金：国家自然科学基金(31860486);贵州省科技支撑项目(黔科合支撑[2020]1Y131号)。

摘　　要：为探索田间猕猴桃溃疡病菌Pseudomonas syringae pv. actinidiae(Psa)致病力丧失的分子机制,针对从猕猴桃果园中分离获得的1株不致病菌株G230,通过特异性引物检测和多基因序列分析明确其分类地位,并设计引物检测其是否由已知遗传变异引起,通过比较基因组学、基因表达、超敏反应和荧光素酶报告菌株检测确定引起菌株G230致病力丧失的原因。结果表明,不致病菌株G230为Psa生物型3(Psa3),其致病缺陷不是由已报道的遗传变异引起;基于基因组比较分析发现菌株G230中的hrpS基因被转座子ISPsy36插入破坏,导致Ⅲ型分泌系统(type Ⅲ secretion system,T3SS)不能正常表达;而在不致病菌株G230中表达hrpS基因后能恢复其T3SS功能,使其具备致病能力及激发非寄主超敏反应的能力。表明转座子ISPsy36插入hrpS基因内部可以破坏Psa的T3SS功能进而使其丧失致病力,这是自然条件下Psa3丧失致病力的一种新型机制。To gain insight into the molecular basis underlying spontaneous loss-of-virulence in natural populations of Pseudomonas syringae pv.actinidiae(Psa),the causative agent of kiwifruit bacterial canker,a non-pathogenic isolate G230 from a kiwifruit orchard was identified using Psa-specific PCR detection and multi-locus sequence analysis,and the genetic cause of the non-pathogenic phenotype was determined with PCR detection of several known transposon-insertion events,comparative genomics and gene expression methods,followed by the detection of type Ⅲ secretion system(T3SS)via a nanoluciferase reporter system and the hypersensitive response(HR)indicator on the non-host Nicotiana benthamiana leaves.The non-pathogenic isolate G230 was identified as Psa biovar 3(Psa3),and results revealed that its loss of virulence was not caused by known transposon-insertion events in Psa3.Moreover,a novel transposon-insertion event inside hrpS gene by ISPsy36 was found in G230,and after expression of the hrpS gene in non-pathogenic isolate G230 resulted in a functional T3SS,which was nec‐essary for pathogenicity in Psa3 and HR induction in non-host plants.Taken together,the insertion of ISPsy36 into the hrpS gene,which results in T3SS deficiency in the non-pathogenic isolate G230,represents a novel mode of action underlying spontaneous loss-of-virulence in natural populations of Psa3.

关 键 词：猕猴桃溃疡病 致病性 转座子 Ⅲ型分泌系统 hrpS基因 

分 类 号：S436.634[农业科学—农业昆虫与害虫防治]