西双版纳5种附生兰非菌根内生真菌多样性研究

从西双版纳纳板河流域国家级自然保护区的盆距兰Gastrochilus、隔距兰Cleisostoma、毛兰Eria、贝母兰Coelogyne和万代兰Vanda的根、茎、叶分离得到172株非菌根内生真菌,根据ITS1-5.8S-ITS2 rDNA系统发育分析鉴定为盘菌亚门的4纲11目29属,其中炭角菌目、肉座菌目和格孢腔菌目真菌的相对频率最高;Xylaria、Fusarium和Phoma为主要优势属,相对频率分别为23.3%、14.5%和10.5%,它们的组织专化性不同,其中Xylaria在根、茎和叶均有分布,而Fusarium和Phoma都分离自根部。不同组织的内生真菌多样性和种类组成差异明显,根、茎和叶的内生真菌Shannon多样性指数分别为2.4083、1.0312和0.6557,表明根部内生真菌多样性显著高于茎、叶内生真菌多样性,其中根的主要优势内生真菌类群有Fusarium、Xylaria和Phoma,茎的主要优势内生真菌类群有Xylaria、Pestalotiopsis和Colletotrichum,叶的主要优势内生真菌类群有Colletotrichum、Pallidocercospora、Pantospora和Phyllosticta。从附生兰种类来看,盆距兰、隔距兰、毛兰、贝母兰和万代兰内生真菌的Shannon多样性指数分别为2.2689、2.2635、2.0115、1.9197、1.7139,表明盆距兰和隔距兰内生真菌多样性高于毛兰、贝母兰和万代兰。

Diversity of non-mycorrhizal endophytic fungi from five epiphytic orchids from Xishuangbanna,China

One hundred and seventy-two isolates of non-mycorrhizal endophytic fungi were isolated from epiphytic orchids, including Gastrochilus, Cleisostoma, Eria, Coelogyne and Vanda, collected in the Naban River Watershed National Nature Reserve in Xishuangbanna. Of them, 29 genera in 11 orders of 4 classes of Pezizomycotina were identified by ITS1-5.8S-ITS2 rDNA sequence analysis. The relative frequency of Xylariales, Hypocreales and Pleosporales was the highest. Xylaria, Fusarium and Phoma were the dominant genera with the relative frequency of 23.3%, 14.5% and 10.5%, respectively. These three genera displayed different tissue specificity. Xylaria could be isolated from all tissues of orchid, however, Fusarium and Phoma were only from roots. Biodiversity and community composition of endophytic fungi in different tissues varied significantly. Shannon diversity index of endophytic fungi in root, stem and leaf tissues were 2.4083, 1.0312 and 0.6557, respectively, showing that diversity of endophytic fungi in roots was significantly higher than that in stems and leaves. The dominant endophytic fungi in roots were Fusarium, Xylaria and Phoma, and in stems Xylaria, Pestalotiopsis and Colletotrichum, while in leaves Colletotrichum, Pallidocercospora, Pantospora and Phyllosticta. Shannon diversity index of endophytic fungi in Gastrochilus, Cleisostoma, Eria, Coelogyne and Vanda were 2.2689, 2.2635, 2.0115, 1.9197 and 1.7139, respectively, indicating that diversity of endophytic fungi in Gastrochilus and Cleisostoma was higher than that in other orchids.