Studies On The Diversity Of Endophytic Fungi From Medicinal Plants In Dendrobium

Dendrobium is an adnascent plant of the orchid family, which includes many species with medicinal value. Endophytic fungi can be found in all kinds of Dendrobium under natural conditions and it plays an important role in the life history of Dendrobium. More attentions have been paid to the endophytic fungi of Dendrobium. However, very few studies have investigated the diversity of endophytic fungi of Dendrobium. The diversity of 542 isolates of endophytic fungi from 24 species medicinal Dendrobium plants was systematically studied in this thesis.Some methods in promoting sporulation were investigated using 77 isolates of endophytic fungi in Maytenus and Anoectochilus for the research material. Low temperature treatment was found to be the best method for promoting sporulation. So this method was used to promote sporulation of isolates in Dendrobium. A new species, Hansfordia pallens, isolated from living leaves of Anoectochilus roxburghii was found in this work.A total of 249 isolates sporulated of medicinal Dendrobium were identified into 21 genus based on morphological characteristics. 148 isolates were identified to species, and they were subordinated to 51 species including 3 new records Acremonium sordidulum, Periconiella cestri, Hyalodendron lignicola. Among them, 14 genus were found in Dendrobium for the first time, Alternaria, Cladosporium, Aureobasidium, Chaetophoma, Periconiella, Nigrospora, Hyalodendron, Thielavial, Pleurophragmium, Melanconium, Glomerularia, Sirodesmium, Chaetomella, Streptomyces in Dendrobium. Fusarium and Acremonium were found to be predominance populations of Dendrobium endophtic fungi.Approach 54% isolates could not produce any spore, although low temperature treatment was done for promoting sporulation. These isolates were divided to 30 morphotypes based on similar cultural characters. Our method was to identify 148 strains of these morphotypes based on phylogenetic analysis of ITS and 5.8S gene sequences, as well as sequence similarity comparison. The results showed that 8 strains were identified to species level, 128 strains to 28 generic level, 10 strains to family level, and 2 strains to order level. Among them, 21 genus were found in Dendrobium for the first time, Arthrinium, Chaetomium, Colletotrichum, Cercophora, Phomopsis, Nectria, Cosmospora, Bionectria, Nemania, Pleospora, Leptosphaerulina, Lewia, Paraconiothyrium, Ampelomyces, Davidiella, Lasiodiplodia, Fusicoccum, Botryosphaeria, Pezicula, Hypocrea. The identification result based on both morphological and molecular characters shows that the kind and amount of endophytic fungi are different according to different species of plants in medicinal Dendrobium.