菌根真菌与石斛属（兰科）药用植物地理分布的相关性研究

Almost all orchids are symbiosis with their fungal partner throughout their lifetime. To investigate mycorrhizae fungal(MF)community composition is very important for understanding biological characteristics and conservation of orchids germplasm,and for community ecological restoration. Dendrobium officinale, D. nobile, D. chrysotoxum and D. fimbriatum are rare Dendrobium (Orchidaceae) medicinal plants included in Chinese pharmacopoeia. Now the wild resources are destroyed and decreased seriously, which make it urgent to carry out researches on MF community composition of Dendrobium medicinal plants. In this research proposal, wild plants of D. officinale, D.nobile, D. chrysotoxum and D. fimbriatum will be collected from at least 5 regions in south China. The pyrosequencing technique will be used to illuminate the composition of MF community,and the relationship between MF community and host geographic distribution will be analyzed. The main component contents and their relation with composition of MF community will be examined and clarified, respectively. The DNA array technique based on sequence information obtained by pyrosequencing will be used to examine and identify the mycorrhizal fungi in samples of original habitat. The interaction between seedlings of Dendrobii and culturable MF will also be carried out. We anticipate the coming results of this research will provide basic data for further application of MF in cultivation of Dendrobii in their original habitat, and will give theoretical support for germplasm conservation and community ecological restoration.

几乎所有兰科植物都与菌根真菌共生，所以研究菌根真菌群落组成对于了解兰科植物的生物学特性、进行兰科植物种质资源保藏及群落的生态恢复尤为重要。铁皮石斛、金钗石斛、鼓槌石斛和流苏石斛为我国药典收录的名贵兰科石斛属药用植物，目前野生资源已日渐枯竭，对石斛属药用植物菌根真菌类群进行系统研究已是当务之急。在本课题研究中，拟对我国南方5个以上地区的金钗石斛、鼓槌石斛、流苏石斛及铁皮石斛野生植株，采用焦磷酸测序技术系统研究其菌根真菌的群落多样性，明确菌根真菌的群落组成是否与宿主植物的地理分布存在相关性；检测每种石斛不同来源样本中的主要成分含量并分析其与宿主植物菌根真菌类群的相关性；采用DNA阵列技术建立原生境中石斛菌根真菌的检测鉴定方法；并对可培养的菌根真菌与石斛幼苗的相互作用进行研究。预期该研究结果将为石斛属药用植物的原生态栽培提供基础数据，并对其种质资源保藏和种群的生态恢复提供理论指导及依据。

铁皮石斛、金钗石斛、鼓槌石斛和流苏石斛为我国药典收录的名贵兰科石斛属药用植物，目前野生石斛资源已日渐枯竭。虽然我国南方已有多个地区开展石斛类药材的人工栽培，然而当前的栽培技术却改变了兰科植物与菌根真菌共生的天然特性，菌根真菌的缺失无疑影响该类药材的道地性。本项目欲明确野生条件下石斛菌根真菌区系组成是否与其宿主植物的地理分布有关，石斛菌根真菌是否和宿主植物的主要成分含量存在相关性，以及菌根真菌是否对石斛苗的形态建成产生明显影响。我们研究发现石斛属药用植物的菌根真菌主要类群是胶膜菌科真菌；另外有少量的小纺锤菌目、蜡壳耳目以及角担菌科真菌。菌根真菌区系组成与石斛属药用植物的地理分布存在一定的相关性，随着宿主植物地理分布的不同，菌根真菌区系组成通常表现出明显的差异。石斛属不同种植物的优势菌根真菌类群并不相同。通过菌根真菌对铁皮石斛幼苗生长影响的栽培实验，获得了2株对铁皮石斛幼苗干重有增加效应的菌株，以及1个有利于铁皮石斛多糖积累的菌根真菌组合。胶膜菌科真菌为有利于铁皮石斛幼苗生长的真菌种类，而角担菌科真菌能够促进铁皮石斛幼苗多糖的累积。这些研究结果有望应用于石斛属药用植物野生种群的生态恢复及人工栽培中。