丛枝菌根真菌与暗隔内生真菌共生体抗黄瓜根结线虫病的作用机制

Arbuscular mycorrhizal fungi (AMF) and dark septate endophytic fungi(DSE) can jointly colonize plant roots and form symbionts under natural conditions. It has been proved that AMF have the role of antagozing pathogens and inducing plant disease resistance, while DSE also show their effetcs on inhibiting pathogens and reducing plant disease. Both AMF and DSE effects on soil-borne disease of plants and their biocontrol potential have been paid more attention to in recent years. AMF-DSE-root knot nematodes interaction regulating systems will be employed in the present research to mainly investigate: 1) on the basis of confirming species compositions of DSE in the roots of cucumber(Cucumis sativus) grown in protective cultivation, through inoculating cucumber seeds and/or seedlings with AMF and/or DSE in different time and different order, to determine the features of the dual symbionts formed with AMF and DSE, and their interrelationship; 2) based on the above results, with the target of root knot nematode (Meloidogyne incognita), to confirm the effects of different species combinations of AMF and DSE on root knot nematode disease of cucumber plants; 3) on the basis of obtaining the optimum AMF and DSE species combinations which are resistant to the root knot nematodes, the functioning mechanisms of resistant to root knot nematode disease of cucumber plant by the symbionts formed with AMF and DSE should be elucidated on the three levels of cucumber root knot nematode disease phenotypes, the symbiotic ultrastructure features and the cucumber transcriptome expression.The finding of this research is expected to provide theory foundations and technique support for initiating new pathways in researching biocontrol of plant diseases and developing new environmental friendly controlling techniques.

丛枝菌根真菌与暗隔内生真菌可共同侵染植物根系形成共生体。丛枝菌根真菌具有拮抗病原物和诱导植物抗病性的作用，而暗隔内生真菌也表现出抑制病原物减轻病害的效应。这两类真菌对土传病害的抑制作用及其生防潜力日益倍受关注。本项目围绕丛枝菌根真菌-暗隔内生真菌-根结线虫三者构建的互作体系，重点研究：1）在明确设施栽培黄瓜根内暗隔内生真菌种类组成的基础上，通过不同时间和顺序对黄瓜接种丛枝菌根真菌和/或暗隔内生真菌，明确共生体发育特征及相互关系；2）于此基础上，以南方根结线虫为靶标，明确丛枝菌根真菌与暗隔内生真菌不同组合菌种控制黄瓜根结线虫病害的作用。该研究结果可望为开创植病生防研究的新途径和研发绿色防控的新技术提供理论依据和技术支持。

自山东莱阳、寿光和莱西等设施蔬菜主产区选择黄瓜样地，从不同连作年限、黄瓜生育期和土层深度分别采集黄瓜根系和根区土壤；观察根内AMF与DSE形态特征、测定AMF和DSE侵染数量、分析AMF或DSE侵染发育数量与黄瓜根结线虫病害的相关性。分子生物学技术鉴定黄瓜根内共有7 种AMF，包括Funneliformis mosseae，Glomus fasciculatum，Glomus indicum，Scutellospora dipurpurescens，Gigaspora margarita 以及两个未培养的Archaeospora；而以黄瓜根段作为接种物加富培养后，依据其所产生的孢子形态特征进行分类鉴定，则只分离获得F. mosseae，G. indicum 和Gi. margarita；同时，采用常规分离纯化的方法从黄瓜根内分离得到DSE 6 个菌株，其中1 株经分子生物学鉴定为Phoma leveillei。 对“津优35 号”黄瓜接种南方根结线虫、Phoma leveillei、Funneliformis mosseae、Glomus versiforme、Acaulospora laevis 和/或Scutellospora aurigloba。结果表明AMF与DSE 能促进黄瓜生长、提高产量和增强抗病性。AMF+DSE 组合处理的菌根和DSE 的定殖数量、株高、茎粗、地上部和根系干重、单株产量等显著优于单接种AMF 或单接种DSE 处理。以F. mosseae + P. leveillei 组合抑制南方根结线虫的发育、降低线虫繁殖数量、根内定殖数量、发病率和根结指数的效果最好。F. mosseae + P. leveillei提高了植株防御酶活性、降低丙二醛含量、增强了对膜脂过氧化作用的缓解能力，从而增强了植物对逆境的适应能力。所获得的优良AMF+DSE组合为进一步研究共生真菌之间的互作效应、协同作用机制和研发绿色防控根结线虫病的技术奠定了基础、创造了条件，而具有重要的理论价值和广阔的应用前景。