Abstract

Previous studies regarding fungal specificity and diversity of the Orchidaceae mainly focus on the mycorrhizal fungi. In contrast, little knowledge of endophytic communities and distributions of non-mycorrhizal fungi in different organs and different sites of orchidsare available. In the present study, we investigated the occurrence and species diversity of culturable endophytic fungi from roots and leaves of terrestrial orchid Bletilla ochraceafrom 5 sites in Guizhou. A total of 1026 fungal strains were isolated, and identified to 88 taxa. The 7 species of Epulorhiza, Ceratorhiza and Sebacina (each with > 5% total relative frequency, Basidiomycetes), and 1 species of Phomopsis (6.38%, Ascomycetes) were found to be dominant in roots. In comparison, 5 species of Colletotrichum, Guignardia andCercospora (Ascomycetes) were dominant from leaves. Different species composition was found from different sites for both roots and leaves, and possible reasons are discussed. There was no or very few overlapping species found between roots and leavesin all sampling sites, indicating potential tissue specificity. The occurrence of fungal species from leaves was found to be significantly affected by geographic and environmental factors, and on the other hand, no significant correlation between fungal occurrence and geographic factors was found from roots.

Key words: Ecological distribution, fungal community, identification, mycorrhizal fungi, Shannon-Wiener diversity index.