白及根部内生真菌多样性研究

白及是地生兰科多年生草本植物,是常见的中草药之一。白及根是白及植株吸收养分和水分的主要场所,开展其根部内生真菌的群落组成及多样性分析,对了解云南原生境白及与根部内生真菌间的共生关系具有重要意义。本研究采用形态学和ITS rDNA分子系统发育分析相结合的方法进行菌株鉴定。结果表明,3个采样点的白及根部分离到可培养内生真菌32株,包括9个目、13个科、16个属。其中木霉属Trichoderma、镰刀菌属Fusarium、拟盘多毛孢属Pestalotiopsis为优势类群,分别占总物种数的21.88%、18.75%、9.38%;中碳垫菌属Nemania、丛赤壳属Nectria、炭角菌属Xylaria、紫霉属Purpureocillium、刺盘孢属Colletotrichum、黑孢子菌属Nigrospora、Biscogniauxia、腐质霉属Humicola、脉孢菌属Neurospora、拟茎点霉属Phomopsis、植物腐霉Phytopythium、毛霉属Mucor、伞状霉属Umbelopsis为常见内生真菌类群。α多样性指数分析表明：各采样点的白及根部内生真菌物种多样性最高的是昆明市水源保护区采样点（D=0.799,H’=1.698）,保山市龙陵县采样点物种多样性最低（D=0.787,H’=1.580）。β多样性分析采样点之间的Jaccard（0.912-0.993）、Bray-Curtis（0.838-0.986）和UniFrac（加权0.618-0.631;不加权0.770-0.799）距离,结果表明3个采样点之间的内生真菌群落组成存在差异。3个采样点的不同地理环境和土壤类型给白及提供了不同的生境条件,是影响白及根部内生真菌物种丰度和群落组成差异的主要因素之一。

Diversity of endophytic fungi associated with Bletilla striata roots

Bletilla striata, a geophytic perennial orchid, is a traditional Chinese medicinal herb. Analysis of composition and diversity of endophytic fungi associated with B. striata roots under habitats in Yunnan Province is of great significance in studying the symbiotic relationship between B. striata and endophytic fungi. The fungi were identified by morphology and ITS rDNA phylogenetic analysis. A total of 32 isolates of culturable endophytic fungi was isolated from the roots of B. striata collected from 3 sampling sites, and they were classified as 9 orders, 13 families and 16 genera. Among them, species of Trichoderma, Fusarium and Pestalotiopsis were dominant, accounting for 21.88%, 18.75% and 9.38% of the total species respectively. Species of Nemania, Neonectria, Xylaria, Purpureocillium, Colletotrichum, Nigrospora, Biscogniauxia, Humicola, Neurospora, Phomopsis, Phytopythium, Mucor, and Umbelopsis were found to be common in root tissues. The results of alpha diversity analysis showed that species diversity of endophytic fungi in the root of B. striata was the highest (D=0.799, H’=1.698) in the samples collected at headwater conservation district of Kunming and lowest (D=0.787, H’=1.580) in the samples collected at Longling County, Baoshan City. The Jaccard (0.912-0.993), Bray-Curtis (0.838-0.986) and UniFrac (Weighted 0.618-0.631, Unweighted 0.770-0.799) distances among samples were obtained by beta diversity analysis, indicating difference in species composition of endophytic fungal community in the samples collected from different sites. Soil and habitats are the main factor influencing the diversity of endophytic fungi and community composition in the roots of B. striata.