铁皮石斛位列中华九大仙草之首，水溶性多糖为其主要功效成分，具有抗炎、增强免疫、抗肿瘤等药理活性。课题组在铁皮石斛品种选育及栽培研究中发现，从铁皮石斛茎中分离的内生真菌Pestalotiopsis sp. DO14能极显著提高茎中水溶性多糖的含量。本项目以内生真菌Pestalotiopsis sp. DO14为研究材料，以接DO14菌与无菌铁皮石斛无性系组培苗为研究对象，利用HPLC-MS糖谱法和代谢组学技术揭示DO14对铁皮石斛组培苗多糖成分变化的影响规律，结合铁皮石斛组培苗形态解剖、光合生理特性研究，明确在DO14作用下与多糖变化相关的生长生理特性，同时利用转录组学挖掘DO14作用下与铁皮石斛多糖变化相关的关键酶基因，从而阐释内生真菌DO14促铁皮石斛多糖成分积累的作用机制，为揭示内生真菌影响铁皮石斛品质及其机制提供理论依据，对铁皮石斛药材品质稳定和提升具有重要意义。

Dendrobium officinale is ranked “the first of the nine Chinese fairy herbs”. Water-soluble polysaccharides are its main ingredients, which exhibit anti-inflammatory, immuno-enhancing, anti-tumor and other activities. Our previous studies had found that endophytic fungi Pestalotiopsis sp. DO14 isolated from the stem of D. officinale could significantly improve the content of polysaccharides in the stem. Therefore, this study will focus on how the fungus DO14 affects the polysaccharides accumulation. Sterile clonal tissue-culture seedlings of D. officinale and the seedings co-cultured with DO14 will be studied as subjects. The impact of the target strain DO14 on the regularity of polysaccharides changes in D. officinale plantlets will be revealed by using HPLC-MS saccharide mapping combined with metabonomic technology. Also, the impact of DO14 on the growth and physiological characteristics of D. officinale plantlets that related to the changes of polysaccharides will be clarified by observing microstructure and determining photosynthetic physiological index of D. officinale plantlets. And the transcriptomic technology will be applied to find the key enzyme genes involved in polysaccharides biosynthesis. Then, the mechanism that endophytic fungi DO14 affect polysaccharides of the host plant will be explained. This study is intend to provide scientific evidence for revealing the mechanism that endophytic fungi affect the quality of the medicinal plants, and also has important significance to improve the quality of D. officinale.