西瓜噬酸菌调控因子aryR的基因功能分析

Functional study on the global regulation factor aryR of Acidovorax citrulli Aac-5 strain

瓜类细菌性果斑病是危害葫芦科作物的世界性病害,其病原菌为西瓜噬酸菌(Acidovorax citrulli)。以西瓜噬酸菌野生型菌株Aac-5为研究对象,构建了转录调控因子aryR的全基因缺失突变株,并构建了互补菌株。测定了野生型、突变株和互补菌株的致病性、致敏性、生物膜形成能力和运动能力等生物学特性。同时,使用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,aryR的缺失降低了Aac-5对西瓜的致病力和运动能力,增强了生物膜形成能力,对非寄主烟草仍具有致敏性。hrpE、hrcN、fliR、fliC基因在突变株中的表达量下调,表明aryR对hrpE、hrcN、fliR、fliC基因均为正调控。综上所述,基因aryR在Aac-5致病过程、运动能力和其他表型中起着重要的调控作用。

Bacterial fruit blotch(Acidovorax citrulli)is a serious worldwide disease on cucurbitaceous plants. In this study,a full-gene deletion mutant strain of the global regulatory factor aryR was constructed based on the wild-type strain Aac-5 of A. citrulli through homologous recombination, as well as the complementation strain. The virulence, hypersensitive on tobacco, swimming and twitching motility and the ability of biofilm formation of the wild-type strain, mutant and complementation strain was determined. The expression of flagellum-assembly genes fliR and fliC, and Type III secretion-related genes hrpE and hrcN were also quantitatively assessed by using qRT-PCR. The results showed that compared with the wild type, the virulence, twitching and swimming motilities was decreased in mutant strain, while its biofilm formation ability was increased. The ability of aryR mutant strain on causing hypersensitive reaction on non-host tobacco was maintained. Compared to the wild-type strain, the fli R and fliC genes were lowly expressed in the mutant strain, and the hrpE and hrcN genes were also lowly expressed, suggesting that the aryR positively regulates fliR, fliC,hrpE, and hrcN genes in Aac-5 strain of A. citrulli. In summary, the aryR plays an important role in regulating the virulence, twitching and swimming motilities and biofilm formation of A. citrulli Aac-5 strain.