M60家族肽酶参与调控蜡质芽胞杆菌AR156防治南方根结线虫病的作用机制

【背景】南方根结线虫(Meloidogyne incognita)寄主范围广泛,能侵染茄科、豆科、葫芦科等蔬菜,对世界农业生产造成了严重危害,每年造成的损失可高达数百亿美元。蜡质芽胞杆菌(Bacillus cereus) AR156是一种革兰氏阳性杆状细菌,对于南方根结线虫引起的土传病害有较好的防治效果,并且已经完成了全基因组测序。【目的】了解AR156对南方根结线虫的生防机理,寻找与生防功能相关的基因,进行遗传功能基因的分析。【方法】构建蜡质芽胞杆菌AR156 miniTn10随机插入突变体文库,通过对南方根结线虫致死率和温室防病试验进行筛选,找到与AR156生防能力相关的突变体,鉴定相关功能基因,并对产蛋白酶活性、定殖能力、生物膜形成和游动性等方面进行检测。【结果】与AR156野生型相比,转座子插入位点在M60家族肽酶的突变体BC41产蛋白酶活性下降,植物根围定殖能力减弱,生物膜形成能力和游动性受到影响,从而导致其防治南方根结线虫的能力降低。【结论】通过对生防相关功能基因的分析,初步明确M60家族肽酶在蜡质芽胞杆菌AR156防治南方根结线虫的过程中发挥重要作用。

Mechanism of M60 family peptidase of Bacillus cereus AR156 involved in biocontrol against Meloidogyne incognita

[Background] Meloidogyne incognita has a wide range of hosts to infect including Solanaceae, Leguminosae, Cucurbitaceae and other vegetables. It causes serious damage and tens of billions of losses to the global agricultural production every year. Bacillus cereus AR156 is a gram-positive and rod-shaped bacterium that can be used as a biocontrol agent to control M. incognita, and has complete genome-wide sequencing. [Objective] In order to understand its biocontrol mechanism against M. incognita and to search for the related gene of biocontrol function, we analyzed the functional gene of B. cereus AR156. [Methods] We screened mortality of M. incognita and biocontrol efficiency under greenhouse in the AR156 miniTn10 random insertion transposon library to find mutants associated with biocontrol ability in AR156. Gene involved in biocontrol in AR156 was identified. And we compared producing-protease ability, colonization, biofilm formation and swarming motility. [Results] Compared with the AR156 wild-type, BC41 had reduced production of protease, colonization of plant rhizosphere, formation of biofilm and swarming motility. Its insertion site is the M60 family peptidase, which decreased the ability to biocontrol M. incognita. [Conclusion] M60 family peptidase plays an important role in the biocontrol activity of B. cereus AR156 by the analysis of biocontrol-related functional gene.