两株芽胞杆菌生物膜互作在番茄青枯病防治中的作用

The wide host range and genetic diversity of Ralstonia solanacearum make the bacterial wilt difficult to control and a devasting plant disease worldwide. Previous study showed that the mixture of Bacillus cereus AR156 and B. subtilis SM21 significantly enhanced their biocontrol efficacies against bacterial wilt. Recent study revealed that AR156 extracellular substance induced the biofilm formation of SM21. In this project we will purify the active substance, identify its molecular structure by gas chromatography-mass spectrometry (GC-MS), and verify biofilm-inducing activity with the pure chemicals. Then, we will detect the substance on the mutants of the known biofilm related genes to seek its potential sensors and explore the regulation mechanisms underneath its biofilm-activating activity. On the other hand, we will study the substance’s effect on SM21 in transcription level by transcriptome sequencing; construct significantly differentially expressed gene-mutants to study the functions of B.subtilis’ unknown genes in environmental signals sensing and biofilm inducing processes, as well as figuring out their roles in the known biofilm regulation map. In researches on the both above-mentioned aspects, we will verify the biocontrol efficiencies of the mutants and wild type of B. subtilis SM21 against tomato bacterial wilt by greenhouse experiments. This study attempts to, from the perspective of biofilm formation, unravel the mechanism of synergistic control effect achieved by bacterial interspecies interaction, providing theoretical guidance for multi-strain biocontrol agents in both research and industry fields.

茄劳尔氏菌广泛的寄主范围与复杂的群体多样性使得植物青枯病成为世界难题。前期试验中，混合施用生防蜡质芽胞杆菌AR156与枯草芽胞杆菌SM21能够显著增强单菌对青枯病的防治效果。近期发现，AR156胞外物质可促进SM21生物膜形成。本项目拟对该胞外物质进行分离纯化，气-质联用鉴定结构，用纯品验证该物质对生物膜的诱导活性。在此基础上，一方面检测该物质对已知生物膜基因缺失突变体的活性，探究其识别机制以及激活生物膜的调控机理。另一方面通过转录组测序分析该物质对SM21转录水平的影响，构建差异转录基因突变体，研究未知基因在SM21识别环境信号、激活生物膜过程中的作用；以及在已知生物膜调控途径中所处的位置。上述研究中均利用温室试验进行各突变体与野生菌对番茄青枯病的防治功能验证。本项目将从生物膜角度诠释细菌通过种间互作协同防治植物病害的机理，为多菌合剂类生物农药、生物肥料的研究及产业化提供理论指导。

茄劳尔氏菌广泛的寄主范围与复杂的群体多样性使得植物青枯病成为世界难题。前期试验中，混合施用生防蜡质芽胞杆菌AR156与枯草芽胞杆菌SM21能够显著增强单菌对青枯病的防治效果。近期发现，AR156胞外物质可促进SM21生物膜形成。本项目对AR156胞外物质通过固相萃取进行分离纯化，鉴定发现蜡质芽胞杆菌胞外多糖对枯草芽胞杆菌生物膜形成具有广谱的诱导活性。在此基础上，检测该物质对已知生物膜基因缺失突变体的活性，探究发现胞外多糖的识别依赖于蜡质芽胞杆菌KinC的识别。通过构建缺失基因突变体验证了这一结论，并发现两株芽胞杆菌的互作与其在植物上的定殖能力有相关性。本项目从生物膜角度诠释细菌通过种间互作协同防治植物病害的机理，为多菌合剂类生物农药、生物肥料的研究及产业化提供理论指导。

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