The Invisible Engine of Cymbidium goeringii Nutritional Growth - Mycorrhizal Symbiosis

More than 80% of all terrestrial plant species are symbiotically associated with mycorrhizal fungi. This study revealed that the orchid endomycorrhiza and pine ectomycorrhiza have similar symbiotic culture. We addressed the long-standing question that whether the two investigated fungus are belong to completely different symbiotic groups or reflect the same species in different hosts with different symbionts. Mycorrhizal fungi were isolated from the photosynthetic orchid Cymbidium goeringii and identified as members of Ceratobasidiaceae by metagene method and phylogenetic analysis of the internal transcribed spacer (ITS) region of ribosomal DNA. It is an ectomycorrhizal fungus formed by Pinus yunnanensis . The ITS sequences were similar among geographically separated samples obtained from Golden Temple National Park in Kunming city of Yunnan province. The isolated fungus, KMGT47, formed ectomycorrhiza on seedlings of Pinus yunnanensis in pot culture. This suggest that tripartite symbiosis exists between C. goeringii , mycorrhizal fungi, and P. yunnananses in nature, and carbon compounds could be supplied from P. yunnananses to C. goeringii through the hyphae of the mycorrhizal fungi. To the best of authors’ knowledge, this is the first study the suggest the involvement of Ceratobasidiaceae fungi in tripartite symbiosis with photosynthetic orchids and photosynthetic host plants. It was verified by metagene and polygenic phylogenetic analysis.