Identification And Diversity Research Of Endophytic Fungi From Orchids Roots In Yachang, Guangxi

Endophytic fungi can improve the disease resistance of host plants and assist the plants absorbing nutrients. The role of endophytic fungi is particularly important to orchids. It not only can provide carbon source for orchids, but connect the underground and overground ecosystem closely. In order to understand the function of endophytic fungi in the growth and development of orchids as well as ecological role in the system, the roots of 24 species of Orchidaceae were collected from Yachang, Guangxi province, including Cymbidium lancifolium, Cymbidium cyperifolium, Cymbidium goeringii, Cymbidium aloifolium, Cymbidium tracyanum, Cymbidium bicolor, Malaxis biaurita, Liparis nigra, Liparis chapaensis, Bletilla ochracea, Goodyera schlechtendaliana, Cleisostoma rostratum, Cleisostoma williamsonii, Eria coronaria, Eria comeri, Bulbophyllum andersonii, Oberonia iridifolia, Panisea tricallosa, Panisea cavalerei, Pholidota yunnanensis, Vanda concolor, Kingidium braceanum and Coelogyne fimbriata After reseached their mycorrhizal microstructure, isolation and identification of the endophytic fungi from the roots were finished. The results were showed as the following:1. Mycorrhizal microstructure:Terrestrial species, such as Bletilla ochracea usually has light-color and hairchested roots. Epiphytic orchids usually have deep color and slender roots. Generally, terrestrial species are lack of velamina, but epiphytic orchids have. Casparian bands of terrestrial species are usually blurry but which of epiphytic species are clear. Starch powder and needle crystal can be observed in some root samples.2. Fungal isolation and identification:There are 136 fungal strains obtained from 22 species, except Panisea tricallosa and Eria corneri. The molecular phylogeny indicated that the fungi mainly belonged to Xylariales, Hypocreales, Eurotiales, Dothideales, helotiales, Pleosporales, Pezizales of Pezizomycotina, Mortierellales of Mortierellomycotina, Cantharellales, Agaricales, Polyporales of Agaricomycotina.3. Diversity analysis:Simpson diversity index (D) and pielou’evenness index of root endophytic fungi of orchids growing in summer were both higher than in autumn. Two indexs of root endophytic fungi of orchids in growing stage were both higher than in mature. Two indexs of root endophytic fungi from orchids lived at an altitude from 800m to 1600m both were higher than those at any other altitude. The diversity of root endophytic fungi in a certain period may be a result of temporary balance between the external environment and its internal physiological needs.