Correlation Between Mycorrhizal Fungi And Geographical Distribution Of Dendrobium Medicinal Plants (Orchidaceae)

In this paper, we studied the correlation between mycorrhizal fungi and geographical distribution of four medicinal Dendrobium species, including D. chrysotoxum, D. fimbriatum, D. nobile and D. candidum, which are listed in the Chinese Pharmacopoeia. Moreover, the influence of six mycorrhizal fungi on D. candidum seedlings growth was studied. The results were as follows:The identified mycorrhizal fungi of D. chrysotoxum mainly belonged to the Tulasnellaceae and Atractiellales, which accounted for 63%,37%, respectively; Tulasnellaceae are distributed in D. chrysotoxum from different regions, but Atractiellales only distributed in the sample of Xishuangbanna. There were significant differences in the fungal composition of D. chrysotoxum from different regions. The identified mycorrhizal fungi of D. fimbriatum mainly belonged to Tulasnellaceae and Sebacinales, specifically, Tulasnellaceae were dominant taxa for the relative abundance of 99.7%, but fungal community in D. fimbriatum from different regions had obvious differences. Mycorrhizal fungi isolated from D. nobile all belonged to Tulasnellaceae. Although there are some differences in dominant species of plant material of different geographical distribution, the composition of mycorrhizal fungal communities is not different significantly, and they show obvious mycorrhizal specificity. Mycorrhizal fungal taxa of D. candidum mainly belonged to Tulasnellaceae which relative abundance was 81.4%. At the same time, Ceratobasidiaceae, Pluleus sp. and uncultured Basidiomycota species were also found in D.candidum, but they are rare. Obvious differences appear in the composition of mycorrhizal fungal communities D. candidum from different regions. The mycorrhizal fungi of different plants were different, and the differences of mycorrhizal fungal taxa in the same plant species from different geographical distribution are related to the species of the host plants.Geographical distribution of Dendrobium medicinal plants have certain correlation with mycorrhizal fungal community composition, and mycorrhizal fungi community composition typically exhibit significant differences due to geographical distribution difference of their host plants.The experiments of mycorrhizal fungi effect on D. candidum seedlings growth were carried out,2 strains of D. candidum and one prescription of strains were obtained. The 2 strains can increase the seedling dry weight, and the combination of strains was in favor of D. officinale polysaccharide accumulation. Tulasnellaceae, dominant mycorrhizal fungal taxa, involved in this paper, is conducive fungal species to the growth of D. candidum seedlings. Ceratobasidiaceae can promote the accumulation of polysaccharide in seedlings of D. officinale.As a result, certain correlation exists between mycorrhizal fungi community composition and host plant geographical distribution, and mycorrhizal fungi may related with ecological adaptability of host plants. These results provide a support for the application of mycorrhizal fungi into cultivation of Dendrobium medicinal plants, and will lay a foundation for further functional research regarding wild population’s ecological recovery of Dendrobium genus.