解淀粉芽孢杆菌T-5易挥发性有机物抑制土传青枯病的机制研究

Volatile organic components (VOCs) emitted from bacteria have significant influence to other microbes. Could VOCs from bacterial antagonists suppress soil-borne plant disease (the competitor of antagonists), like odour of skunks can prevent invaders and competitors? Could it affect pathogen invasion or plant resistance, like nerve gas affects animal's temperament and behaviour? Previous studies showed that the biocontrol agent Bacillus amyloliquefaciens strain T-5 could efficiently control the bacterial wilt disease of tomato caused by the soil-borne phytopathogen Ralstonia solanacearum. Further study showed that the VOCs produced by B. amyloliquefaciens T-5 could affect the growth of R. solanacearum, which indicated that VOCs of strain T-5 might play an important role in controlling the Ralstonia wilt disease. Here we hypothesize that the VOCs of strain T-5 are involved in disease control via three different mechanisms: 1) reduce the growth of pathogen; 2) inhibit the virulence traits of pathogen and 3) induce plant defense system. We will use GC-MS to identify the VOCs produced by strain T-5, and those VOCs will be evaluated for their effects on the growth and virulence traits of pathogen and induction in systemic resistance in plants. We will also study the effect of temperature and nutrient sources on the production of the key VOCs by strain T-5. We expect that novel products or technologies could be developed for successful control of bacterial wilt disease by understanding the functions of microbial VOCs.

研究发现微生物代谢物中易挥发性有机物（Volatile Organic Components, VOCs）对其功能发挥起重要作用。那么根际生防菌产生的VOCs是否具有像臭鼬排出的臭气有效抵御入侵者和竞争者一样具有抑制植物土传病原菌（生防菌竞争者）生长的功效？是否类似于神经毒气影响动物的性情和行为一样影响病原菌的侵染特性或植物抗病能力？研究发现生防菌T-5能有效防控土传番茄青枯病，其产生的VOCs显著影响了致病青枯菌的生长特征，我们推测T-5菌株VOCs组分可能通过作为代谢致弱（抑制病菌移动和摄取资源能力）、毒性调控（调控病菌致病基因表达）和抗病诱导（诱导植物抗病）因子参与抑制土传青枯菌侵染过程。拟通过GC-MS检测T-5菌株VOCs组分；探究不同组分在青枯菌代谢致弱、毒性调控和抗病诱导中的作用，鉴定出关键VOCs组分；并探究影响关键组分产生的环境因素，为后期应用开发提供理论和技术支撑。

在防控土传病害的研究中，生防菌VOCs在抑制病原细菌的作物侵染方面可能发挥着重要的作用，但其机制尚不清楚。生防菌解淀粉芽孢杆菌 T-5是一株高效生防菌，具有很强的根际定殖能力。T-5能分泌多种拮抗物质，诱导番茄抗病基因表达，高效抑制土传病原菌侵染番茄根系，并显著降低病害的发生。为了探究其产生的VOCs是否能在抑制病害上发挥重要的作用以及作用机制，我们用收集的T-5产生的VOCs处理青枯菌，探究其对青枯菌生长、代谢、致病基因表达以及提高植物抗性等途径的影响。研究结果发现：1）T-5产生的VOCs能显著抑制青枯菌的生长能力，而且这种抑制作用随VOCs浓度的增多而增强。2）T-5产生的VOCs能显著致弱青枯菌致病相关的特征，如运动能力、生物膜形成能力、胞外多糖产生能力以及根际定殖能力。3）T-5产生的VOCs能通过影响青枯菌抗氧化活性、新陈代谢以及毒性表达有关的蛋白表达来影响青枯菌的细胞功能。4）T-5分泌的VOCs能通过提高番茄体内丙二醛含量和多种抗氧化酶活性来提高番茄抵抗青枯菌侵染的抗性水平。以上结果为生防菌VOCs增强组控土传病害效果的应用奠定了坚实的理论基础。

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