滇西槽舌兰内生真菌多样性及其共生真菌对叠鞘石斛种子萌发的效应

Diversity of Endophytic Fungi in Holcoglossum rupestre and Effects of Symbiotic Fungi on Seed Germination of Dendrobium denneanum

兰科植物种子萌发甚至整个生长阶段依赖于共生真菌。滇西槽舌兰(Holcoglossum rupestre)是我国特有极度濒危物种,为了更好地开展其种质资源保护,采集云南香格里拉、楚雄、昆明盘龙、昆明呈贡的滇西槽舌兰植株,基于ITS rDNA序列对其根部的内生真菌进行分离、鉴定和多样性分析,并研究这些内生真菌对叠鞘石斛(Dendrobium denneanum)种子萌发的影响。结果表明,滇西槽舌兰4个分布地植株的根内共分离、鉴定出68株内生真菌,分别属于粪壳菌纲(Sordriomycetes)、伞菌纲(Agaricomycetes)和座囊菌纲(Dothideomycetes)3个纲18个属。其中,镰刀菌属(Fusarium)、间座壳属(Diaporthe)、胶膜菌属(Tulasnella)、角担菌属(Ceratobasidium)的相对丰度分别为27.94%、10.29%、8.82%、8.82%,为主要优势内生真菌。胶膜菌属和角担菌属为滇西槽舌兰首次分离到的兰科共生菌,且胶膜菌属的P2和P47菌株可以显著促进叠鞘石斛种子萌发进程及萌发一致性。

The germination and growth of orchid seeds depend on symbiotic fungi.Holcoglossum rupestre is an endemic,narrowed distributed and critical endangered species of Orchidaceae.Aiming to better ex situ conserve H.rupestre,the plants were collected from Shangrila,Chuxiong,Kunming Panlong and Kunming Chenggong in Yunnan.The endophytic fungi in its roots were isolated and identified based on ITS rDNA sequences,and their effect on seed germination was studied.The results showed that 68 culturable fungal endophytes were isolated and identified from roots of H.rupestre from 4 localities of Yunnan province,which belonged to 18 genera of 3 classes,i.e.,Sordriomycetes,Agaricomycetes and Dothideomycetes.Among all strains,Fusarium,Diaportha,Tulasnella and Ceratobasidium were the dominant fungal endophytes with 27.94%,10.29%,8.82%and 8.82%of relative abundance.Some orchids mycorrhizal fungi as well as Tulasnella and Ceratobasidium were firstly found in H.rupestre roots.And Tulasnella strains P2 and P47 could significantly promote symbiotic germination of Dendrobium denneanum seeds by advancing germination process and improving germination consistency.