Biodiversity and tissue-recurrence of endophytic fungi in Tripterygium wilfordii

A total of 343 endophytic fungal isolates representing 60 taxa including 30 morphotypes were isolated from the different parts of the Chinese medicinal plant, Tripterygium wilfordii. In most cases fungal strains were only identified to genus because species identification was difficult in these speciose genera. Non-sporulating isolates were designated as Morphotypes 1 to 30. The endophytic assemblages of T. wilfordii comprised a number of cosmopolitan species such as Colletotrichum gloeosporioides, Guignardia sp., Glomerella cingulata, Pestalotiopsis spp., Phomopsis spp. and Phyllosticta sp. The overall fungal community of T. wilfordii was moderately diverse. The fungal community from the twig xylem parts was most diverse, followed by leaves, twig bark, root xylem and flowers. Pestalotiopsis cruenta, Phomopsis sp. B and Phomopsis sp. A were predominantly isolated from the twig xylem and bark. These endophytes were not isolated from the roots, leaves and flowers. Likewise, Glomerella cingulata and Guignardia sp. were predominantly isolated in leaves. Phialophora sp. was isolated only in root xylem. In contrast, Pestalotiopsis disseminata was isolated from all the tissues except root bark. Morphotype sp. 1 was isolated from twig and root segments. Interestingly, root bark only accommodated Morphotype sp. 1 and no other endophytic fungi were isolated from the organ. Pestalotiopsis spp. were frequently isolated as root endophytes in this study. The species composition and frequency of endophyte species was found to be dependent on the tissue type. The dominant fungi isolated from the different tissues of the host expressed a fair degree of tissue-recurrence.