Ⅲ型分泌系统是欧美杨溃疡病菌Lonsdalea quercina重要的致病因子  

Type Ⅲ secretion system is an essential pathogenic factor in poplar canker pathogen Lonsdalea quercina

作　　者：杨莉[1] 张力群[2] 贺伟[1] 常聚普 郭利民 

机构地区：[1]北京林业大学教育部森林培育与保护重点实验室,北京100083 [2]中国农业大学农业部植物病理学重点开放实验室,北京100193 [3]濮阳市林业科学院,濮阳457000

出　　处：《植物病理学报》2014年第5期512-520,共9页Acta Phytopathologica Sinica

基　　金：林业公益性行业专项资助项目(201104054)

摘　　要：欧美杨溃疡病是由Lonsdalea quercina(原称Brenneria quercina,Erwinia quercina)引起的一种细菌性病害,2005年首次在我国河南发现,对我国杨树产业造成了严重影响。菌株N-5-1是从河南濮阳自然发病杨树枝条上分离到的致病菌株。根据N-5-1菌株全基因组测序的初步结果分析,发现N-5-1具有完整的III型分泌系统(Type III secretion system,T3SS)。该系统与植物病原菌Erwinia amylovora CFBP1430和Dickeya dadantii 3937的T3SS高度相似,共由26个基因编码,共约23kb,其中9个为保守的hrc基因。将L.quercina N-5-1菌株T3SS中保守的结构基因hrc V进行缺失突变,生物测定发现Δhrc V突变体对"中林46杨"(Populus×euramericana‘Zhonglin 46’)2年生枝条的致病力明显下降,而互补菌株HBhrc V致病力与野生菌株保持一致。表明该菌中T3SS是病原细菌重要的致病性因子。菌株N-5-1中hrc V基因的突变导致诱导烟草过敏性坏死反应能力丧失,但并没有影响菌株的生长速率、游动性和生物膜的形成。本研究首次证明了L.quercina N-5-1菌株的T3SS是重要的致病因子。Poplar canker caused by Lonsdalea quercina （ formerly Brenneria quercina or Erwinia quercina） was found in Henan Province, China in 2005. The disease affected local poplar industry seriously. Bacterial strain N-5-1 was isolated from naturally infected poplar and identified as the pathogen of canker disease. Based on gene sequence alignment, a complete type III secretion system （T3SS） cluster, similar to that in pathogenic bacteria Dickeya dadantii 3937 and Erwinia amylovora CFBP1430, was identified in the genome sequence of strain N-5-1. The T3SS of N-5-1 had about 23 kb in size including 26 genes, 9 of which were highly conserved hrc genes. To study the role of T3SS in pathogenicity of strain N-5-1, a deletion mutant of the T3SS structural gene hrcV and its complemented mutant were constructed. Pathogenicity assay on poplar branches （Populus Xeuramericana ＇Zhonglin 46＇ ） indicated that the AhrcV mutant was significantly less virulent （disease index 33.3） than its parent, while the complemented mutant HBhrcV restored the virulence to the wild-type level （disease indexes were 85.6 and 83.3, respectively）. The hrcV mutation abolished the HR elicitation activity on tabacco, but didnot influence the bacterial growth, motility and biofilm formation. This study suggests that the T3SS is an essential pathogenic factor in L. quercina N-5-1.

关 键 词：欧美杨溃疡病 Lonsdalea quercina Ⅲ型分泌系统 

分 类 号：S763.13[农业科学—森林保护学]