西瓜噬酸菌中C-di-GMP代谢相关基因Aave2620的功能研究

Functional study on gene Aave 2620 related to C-di-GM P metabolism in Acidovorax Citrulli

环鸟苷二磷酸(cyclic diguanylate,c-di-GMP)是一种广泛存在于植物病原细菌中的第二信使,调控细菌多种生物学功能,从而影响病原细菌的致病性,但其在西瓜噬酸菌中的研究还未见报道。本实验以Aac5菌株为研究对象,通过构建c-di-GMP代谢相关基因Aave_2620缺失突变株和互补菌株,从其致病能力及其生长能力两部分进行测定,探究此信号途径是否在西瓜噬酸菌中调控致病机制。结果表明,基因Aave_2620的缺失显著降低Aac5菌株致病力、生物膜形成能力和生长能力,减弱烟草过敏性反应以及运动能力,互补菌株表型基本得到恢复。基因Aave_2620的缺失显著影响三型分泌系统相关基因、毒性相关基因以及鞭毛及趋化性相关基因在西瓜噬酸菌中的表达量。以上结果表明c-di-GMP代谢相关基因Aave_2620与西瓜噬酸菌的致病密切相关。

Cyclic diguanylate monophosphate (c-di-GMP) is a second messenger in many phytopathogenic bacteria and regulates a variety of biological functions including pathogenicity. However, no functional study on c-di-GMP in Acidovorax citrulli has ever been reported. The gene Aave_2620 in A. citrulli contains domains related to c-di-GMP metabolism. We generated the ΔAave_2620 mutant in A. citrulli strain Aac5, as well as its complementation strain ΔAave_2620comp. The virulence, biofilm formation and bacterial growth were significantly reduced in the mutant ΔAave_2620 compared to its wild-type Aac5. The mutant ΔAave_2620 was also decreased in the ability triggering hypersensitive reaction on non-host tobacco, and decreased in swimming motility. The complemented strain ΔAave_2620comp recovered all aforementioned biological traits. The expression of genes related to Type III secretion system, virulence, flagellum assembly and chemotaxis were significantly affected in mutant ΔAave_2620, indicating the importance of gene Aave_2620 in the virulence of A. citrulli.