群体感应对土传病害高效生防菌--多粘类芽孢杆菌生物膜形成的影响及其与防效之间的关系

To solve the problems of food safety and environment pollution bring by chemical pesticide, micro-pesticide has been developed rapidly in recent years for the advantages of high control efficacy, environment friendly and the safety of animal and human. The control efficacy of micro-pesticides mostly depend on the colonization capacity of the biocontrol agent. Forming biofilm on plant root is important indicate of good colonization capacity of the biocontrol agent for controlling soil-borne disease. Biofilm formation facilitate the promotion of control efficacy of biocontrol agentor controlling soil-borne disease. Regulating biofilm formation is one important function of quorum sensing, a self modulation system of bacteria. There are not any research about the effect on biofilm formation and control efficacy of Paenibacillus polymyxa by quorum sensing have been reported..Here we proposed a project to reveal the effect on biofilm formation and control efficacy of P. polymyxa by quorum sensing with P. polymyxa HY96-2 strain, the biocontrol agent of commercialized P. polymyxa pesticide. The relationship between biofilm formation, control efficacy of P. polymyxa and quorum sensing will be researched firstly by the P. polymyxa（mutant strain）-tomato-bacteria wilt system. The results of this program will further clarify the biocontrol mechanism of P. polymyxa HY96-2, and provide scientific evidence for the optimization of application technic of P. polymyxa pesticide, which is important for the promotion of controlling soil-borne disease with P. polymyxa pesticide in large scale.

为解决化学农药带来的食品安全及环境污染问题，微生物农药因其高效、无污染等优点，近年得到快速发展。生防菌的定殖能力是决定微生物农药能否正常发挥药效的首要条件。在植物根围形成生物膜是防治土传病害生防菌具有良好定殖能力的重要指征，生物膜的形成有利于防效的提高。细菌的自调节系统--群体感应（QS）可以影响生物膜的形成。迄今，QS对多粘类芽孢杆菌生物膜形成的影响及其与防效之间关系未见报道。.本项目拟以国内外首创并已实现产业化的防治青枯病等土传病害的多粘类芽孢杆菌系列微生物农药的生防菌—多粘类芽孢杆菌HY96-2为对象，通过多粘类芽孢杆菌-番茄-青枯病体系，首次开展QS对多粘类芽孢杆菌生物膜形成的影响研究，进而明晰QS与HY96-2防效之间的相关性。本研究不仅可进一步阐明HY96-2防治土传病害的机制，而且可为多粘类芽孢杆菌农药应用技术的优化提供科学依据，对推动其在土传病害防治中的大规模应用具有重要意

随着我国“两减”政策的推行,微生物农药日益受到关注。项目负责人所在实验室与合作企业以多粘类芽孢杆菌（Paenibacillus polymyxa）HY96-2为生防菌开发的微生物农药--10亿CFU/g多粘类芽孢杆菌可湿性粉剂（PPWP）已实现产业化，但对该药剂的生防机制仍待深入研究。生防菌是否具有良好的定殖能力是决定微生物农药能否正常发挥药效的首要因素。能在植物根围形成生物膜是生防菌具有良好定殖能力的重要指征。已有研究表明群体感应（Quorum sensing，QS）系统对生防菌形成生物膜具有调控功能，但迄今文献中有关QS系统对P. polymyxa生物膜的形成是否有影响尚无报道。因此，本项目以微生物农药生产菌株--P. polymyxa HY96-2为对象，以P. polymyxa-番茄-青枯病为体系，首次开展QS对HY96-2菌株生物膜形成影响的研究，并在此基础上开展QS与HY96-2菌株防效的相关性研究。.通过本项目实施：1）明确了luxS是P. polymyxa这个种的QS关键调控基因；2）明确了luxS的过表达可以促进HY96-2菌株生物膜的形成；3）明确了luxS的过表达可以提高HY96-2菌株防治番茄青枯病的能力；4）结合生物膜形成能力及药效评估结果，可以推测，QS可以促进HY96-2生物膜的形成，并进而提高它对番茄青枯病的防效；5) 明确了HY96-2与其他2个P. polymyxa生防菌的生物膜形成主要相关基因的组成相同，但各基因的相似度有一定差异；6）首次推测并发表了P. polymyxa生物膜形成可能途径。.上述研究成果不仅具有重要的学术理论价值，还具有显著地的应用价值。本项目研究推定的“QS可以促进HY96-2生物膜的形成，并进而提高它对番茄青枯病的防效”的结论已用于企业推广PPWP防治植物青枯病时田间应用技术的指导。