杜仲内生菌在植物中的定殖特征及强化抗病机制的研究

Antagonistic endophytes of the medicinal plant would be a new approach of biological control on plant diseases, and the power of colonization in the rhizosphere or in plants for biocontrol strains was a critical factor to prevent plant diseases biologically. The research focused on the theme of "biocontrol resource exploitation and colonization in the rhizosphere or plants", and continued to isolate, identify and phylogenetic analyse the antagonistic endophytes isolated from the Eucommia ulmoides oliv. to clarify community characteristics of antagonistic endophytes. Then the colonization property of biocontrol strains in wheat rhizosphere were analysed to clear the interactions between wheat and biocontrol bacteria through root exudates, and further, to reaveal the colonization dynamics of biocontrol fungi in wheat rhizosphere. Finally, the colonization of antagonistic endophytes in wheat and its effects on disease resistance of wheat were studied, which layed a foundation for improving the colonization ability and biocontrol efficacy of antagonistic endophytes. The research would expand our vision about the functional diversity and application of biocontrol microbial , it was of great significance to biological control of plant diseases.

利用药用植物拮抗内生菌控制植物病害是极具研发前景的生防新策略，而引入的生防菌能否较好地在植物根际或其体内定殖是决定生防成功与失败的关键。本研究围绕药用植物杜仲拮抗内生菌资源发掘及其在植株根际和体内的定殖，以小麦主要病害为靶标，通过资源筛选、鉴定和系统发育分析，阐明杜仲拮抗内生菌种群组成特征；通过研究拮抗菌在小麦植株根际的定殖特征，揭示根系分泌物介导的"小麦-生防细菌"互作关系以及生防真菌在小麦根际的定殖动态；通过分析生防菌在小麦体内定殖机制及对小麦植株抗病性的影响，为提高生防菌的植株定殖能力、稳定和提高防效奠定基础。本项研究将拓展人们对生防微生物功能多样性及其应用的新视角，对植物病害的生物防治意义重大。

本研究围绕药用植物杜仲拮抗内生菌资源发掘及其在植株根际和体内的定殖主题，以安徽省境内霍山、黄山以及合肥三地区的杜仲植物为材料进行内生菌的分离纯化，共获得杜仲内生真菌共391株，内生细菌共44株；通过形态观察、分子测序以及系统发育分析，阐明药用植物杜仲中拮抗内生菌的种群组成特征。以小麦赤霉病、小麦纹枯病、小麦根腐病3种重要病害为靶标，结合离体及其活体实验，获得高效生防内生黑孢菌属DZJ14一株，生防内生枯草芽孢杆菌DZBG07一株。该研究利用绿色荧光标记、稀释涂布以及荧光定量等多种方法，发现生防真菌DZJ14在小麦根际及植株中可定殖，通过诱导小麦植株PPO、POD及PAL等防御酶活性提高，诱导小麦水杨酸（SA）和乙烯（ET）抗病信号通路的形成，增强小麦对病害的抗病性。此外，开展了对生防细菌DZBG07趋化性、生物膜形成能力及产脂肽物质等特性的研究，结果表明DZBG07对小麦根系分泌物有较好的趋化性，枯草芽孢杆菌DZBG07能够产生Fengycin、Surfactin、IturinA、和IturinB等四种脂肽化合物；利用抗生素标记法、电镜观察，结合稀释涂布法，证实生防细菌DZBG07可在小麦中大量定殖，与小麦植株能够形成和谐的共生关系；通过诱导小麦植株PPO、POD及PAL等防御酶活性增强，诱导小麦中的水杨酸（SA）和茉莉酸（JA）信号通路的形成，增强小麦对病害的抗病性，为提高生防细菌的植株定殖能力、稳定和提高防效奠定基础。研究结果将为植物病害的防治提供新型的生防资源和防治策略，对促进植物病害的生物防治有重要的科学意义和应用价值。