西瓜细菌性果斑病菌基因Aave—3192和Aave—2108的功能研究

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西瓜细菌性果斑病菌基因Aave—3192和Aave—2108的功能研究

作者：周迎辉胡方平蔡学清

来源：《热带作物学报》2016年第07期

摘要从本实验室构建的西瓜细菌性果斑病菌菌株A13的Mini-Tn5转座子突变体库中筛选出2株致病性丧失的突变菌株166和167，亚克隆及测序结果表明，突变株166和167 的Tn5插入位点基因编号分别为Aave-3192和Aave-2108。为了进一步明确这2个基因的功能，分别对这2个基因进行互补。生物学试验结果表明，互补菌株恢复对西瓜果实的致病性，且在游动性、群体感应、胞外多糖、生物膜等性状上部分恢复至野生菌株A13的水平，表明这2个基因与该病菌在西瓜上的致病性相关。

关键词西瓜细菌性果斑病菌；基因突变；基因互补；生物学测定

中图分类号 S432.1 文献标识码 A

Abstract Two mutants（166 and 167） lacked of pathogenicity from the mutant library of wild strain A13 （Acidovorax citrulli）of bacterial fruit blotch of watermelon constructed by insertion of transposon Mini-Tn5was screened. The Tn5 inserted genes of mutant166 and mutant167 were Aave-3192 and Aave-2108 respectively by subcloning and sequence blasting. To identify the functions of the two genes， the complementary strains 166hb and 167hb were constructed， and the pathogenicity and some other biological characters were tested. The results showed that the characters of the two strains were recovered on pathogenicity， motility， quorum sensing， exo-polysaccharides， the colonial morphology and biofilm inordinately. Overall， the results indicated that the two genes were related to the pathogenicity of BFB on watermelon.

Key words Acidovorax citrulli；Gene mutation；Gene complement；Biological determination doi 10.3969/j.issn.1000-2561.2016.07.014

西瓜细菌性果斑病（Bacteria Fruit Blotch of Watermelon）是西瓜上重要的病害之一，由西瓜噬酸菌（Acidovorax citrulli， Ac）[1]侵染引起。作为世界性检疫病害，由于缺少有效的管

控措施，近年来已经给多个国家的瓜类产业带来巨大的损失。该病菌的致病机制研究结果表明，Ⅱ型[2]、Ⅲ型[3-6]、Ⅳ型[7-10]、Ⅵ型[11]分泌系统均参与了该病菌的致病，如Johnson等[2]报道了Ⅱ型分泌系统有助于西瓜噬酸菌在西瓜种子到苗期的传播和定殖，还证实Ⅲ型分泌

系统基因hrcC（编码Ⅲ型菌毛蛋白）是重要的致病因子。本研究小组构建了野生菌A13的

Tn5插入突变体文库，通过筛选获得2株致病性丧失的突变菌株166和167，在此基础上，通过亚克隆技术确定Tn5插入基因为Aave-3192（Hypothetical protein）和Aave-2108（Methyl-accepting chemotaxis sensory transducer）。已有研究报道伪茄拉尔氏菌（Ralstonia