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作 者 ：王铁霖, 杨玉文, 关 巍, 赵廷昌

期 刊 ：植物病理学报 2016年 46卷 2期 页码：198-206

关键词：西瓜嗜酸菌；LuxR家族调控因子；luxR4229；

Keywords:Acidovoraxcitrulli, LuxR-typeregulator, luxR4229,

摘 要 ：瓜类细菌性果斑病是葫芦科作物上的一种严重的世界性病害,其病原菌为西瓜嗜酸菌 (Acidovorax citrulli)。本研究以野生型菌株Ac-5为研究对象,通过同源重组双交换的方法,构建了LuxR 家族功能基因luxR₄₂₂₉的全基因缺失突变株,并对突变株进行致病性、生物膜形成能力和运动能力等生物学特性测定。同时,qRT-PCR 定量检测了鞭毛基因fliR 和fliC以及 III 型分泌系统功能基因hrpE 和 hrcN 的表达水平。结果显示:与野生型相比,突变株致病力明显降低,运动能力减弱,而生物膜形成能力增强。fliR、fliC、hrpE 和hrcN基因在突变株中的表达量下调,luxR₄₂₂₉对fliR、fliC、hrpE 和hrcN基因均为正调控。基因luxR₄₂₂₉在对西瓜嗜酸菌致病力、运动能力及生物膜的形成具有重要调控作用。

Abstract:Bacterial fruit blotch caused by Acidovorax citrulli is a world-wide disease that causes serious damages on the cucurbits plants. luxR₄₂₂₉ is a LuxR family member gene in A. citrulli Ac-5 isolated from watermelon. The luxR₄₂₂₉ deletion mutant was constructed by using two-step homologous recombination. The pathogenicity, biofilm formation and the swimming ability of the wild-type Ac-5 and its mutant strains were investigated. Meanwhile, the expression of the genes fliR and fliC encoding flagella proteins and the genes hrpE and hrcN involved in Type III secretion system were also determined by using qRT-PCR. The result showed that the mutant strain had lower pathogenicity, weaker swimming ability, but stronger ability of biofilm formation compared to its wild-type parent. The expressions of fliR, fliC, hrpE and hrcN genes were decreased in the mutant, indicating a positive regulation of luxR₄₂₂₉ to these genes. This study revealed that the luxR₄₂₂₉ gene plays an important regulatory role in the pathogenicity, swimming ability and biofilim formation of A. citrulli.

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