金沙江石斛菌根真菌的多样性及其对宿主耐旱适应性研究

Dendrobium wangliangii is a new species of Dendrobium genus, belonging to the Orchidaceae family. Its stems tightly attached on the bark distinct from other Dendrobium plants. D. wangliangii distibution is extremly narrow, and the wild individuals are very rare. It is an eiphyte with strong drought resistance and mainly distributed in dry-hot walley of Hengduan Mountains in the temperate zone. Its habitat has large difference with other Dendrobium plants, but little is known about diversity of its mycorrhizal fungi and the mechamism of its drought resistance. As the research material, D. wangliangii has a specific advantage distinct from other Dendrobium plants. So the study on diverstiy of mycorrhizal fungi and the mechanism of drought resistance by D. wanglii has important scientific value and practical meaning, to further understand plants' adaptability and adaptation mechanism to arid enviroment.

金沙江石斛（Dendrobium wangliangii）为兰科石斛属（Dendrobium）植物,其茎紧紧地贴附在树皮上，与其他石斛属植物区别明显。该石斛分布极其狭窄，野外个体非常稀少，是一种耐旱性较强的附生植物。主要分布于温带横断山脉的干热河谷，其生境与石斛属其他植物差异较大，而它的菌根真菌多样性及耐旱适应性研究尚未见报道。作为研究材料具有其它石斛属植物没有的优势，本项目通过研究其菌根真菌的多样性及其对宿主耐旱适应的生理特性影响和耐旱型基因，进一步了解植物对干旱环境的适应能力和适应机制，具有重要的科学价值和实践意义。

金沙江石斛（Dendrobium wangliangii）为兰科石斛属（Dendrobium）植物，分布于金沙江干热河谷，分布区域狭窄，种群数量较少，耐旱性较强。本项目针对金沙江石斛的菌根真菌进行分离鉴定，并对其耐旱活性进行了研究，将耐旱性较强的菌株接种到铁皮石斛组培苗上，在人工干旱胁迫下，检测其对接种寄主耐旱性适应性的影响。目前，取得了阶段性进展，我们分离到金沙江石斛的内生真菌640株，经鉴定属于八个属的真菌。经耐旱活性筛选研究，筛选到6株耐旱性较强的菌株，接种到石斛组培苗后，可以与寄主形成共生关系。在人工干旱胁迫下环境下，有3株真菌可以显著提高寄主的耐旱适应性，可以提高寄主叶绿素a的含量，降低丙二醛（MDA）的水平，同时耐旱相关基因的表达量有所上升。这些结果表明，金沙江石斛的内生真菌丰富多样，干湿季内生真菌种类有所差异。筛选到的菌根真菌和寄主形成了共生结构，因而提高了寄主的耐旱适应性。本项目研究结果为金沙江石斛耐旱适应性及种群保护提供了一定的研究基础。