黄瓜内生真菌多样性及其对土传真菌病害的生防潜能

Cucumber is an important cultivated crop plant. However a variety of diseases occur during their growth period, especially soil-borne fungal diseases which lead towards great economic losses in the production. The diversity of endophytic fungi in cucumber was abundant, formed the complex interactions with cucumber by long-term symbiosis. Endophytic fungi play important roles in plants, increasing the fitness of plant hosts by enhancing their resistance to abiotic and biotic stresses, while that of prevention of soil-borne fungal diseases by endophytic fungi have not been well understood up to date. The aims of current proposal are 1) to determine the different of richness and diversity by investigating the microbial community of the root, stem and the leaves of cucumber which are from continuous cropping soil and rotation cropping soil respectively; 2) to lay the foundation for strain screening and utilization by detecting the antagonistic interactions between the dominant microbes and plant pathogens, and analysis of second metabolism; 3) to determine the colonization ability of endophytic fungi in cucumber and soil by culture dependent and culture independent methods; 4）to observe and determine the distribution of endophytic fungi in cucumber, root, stem and host plant leaves by in situ hybridization localization analysis. The results will not only provide a basis for the application of endophytic fungi, but also provide the resources for prevention of soil-borne fungal diseases.

黄瓜是重要的栽培植物，在其生育期中可发生多种病害，尤其土传真菌病害，常给生产带来重大经济损失。黄瓜内生真菌具有丰富的物种多样性，长期与黄瓜共生形成了复杂的互作关系，对促进黄瓜生长和抵御病害具有重要作用。本项目拟通过对轮作和连作障碍土壤栽培条件下的健康黄瓜根、茎及叶片内生真菌的多样性进行研究，确定在不同耕作条件下，黄瓜内生真菌的丰富度和多样性组成差异；通过优势真菌类群拮抗关系测定及其次生代谢产物活性分析，为具有生防潜力的内生真菌筛选和利用奠定基础；通过内生真菌回接试验，利用培养和非培养的方法，揭示内生真菌在植物体内和土壤中的定殖能力；通过荧光原位杂交技术，探讨内生真菌在植物体内的扩展能力。研究结果不仅为内生真菌的应用提供依据，而且也为土传真菌病害的防治提供资源。

黄瓜（Cucumis sativus Linn.）在世界多地都有种植，但在栽培过程中经常发生多种病害，尤其以土传病害危害较重，严重影响黄瓜的产量和品质，甚至造成绝收。内生真菌几乎存在于所有植物中，种类繁多，许多内生真菌具有促进植物生长发育、增强宿主植物对病虫害的抗性以及对非生物胁迫的抗性等作用。本项目利用培养和非培养方法对轮作和连作障碍黄瓜不同器官中内生真菌进行分离，共获内生真菌1500余株；通过形态学和分子生物学方法对所分离菌株进行鉴定，共得到内生真菌84属，232种，其中疑似新种8个，发表新种4个；通过高通量测序，明确了非培养条件下黄瓜内生真菌的多样性和群落组成情况，为发现有应用价值的真菌资源提供了有效参考；通过1000余株内生真菌的平皿对峙试验，发现47.1％的内生真菌对至少一种病原真菌表现出拮抗作用，其中186 株拮抗Rhizoctonia solani，371 株拮抗Sclerotinia sclerotiorum，403 株拮抗Fusarium oxysporum f. sp. cucumerinum。通过对抑病作用较好的两个内生真菌菌株F30 和F83 的盆栽实验和转录组分析，验证了其对黄瓜根部的定殖作用，并阐明其抑菌作用机制，初步揭示了其对黄瓜抵御病害相关基因表达的影响。研究结果为瓜类植物内生真菌资源的发掘利用及内生真菌、生防真菌相关研究提供了新的依据。