Influence of host tree species on isolation and communities of mycorrhizal and endophytic fungi from roots of a tropical epiphytic orchid, Dendrobium sinense (Orchidaceae).[Pubmed: 28685256]

Most studies on the host preference of orchids have focused on the association between orchids and host characteristics, but little is known about the differences of mycorrhizal and endophytic fungal communities in epiphytic orchids growing on different host tree species. We selected Dendrobium sinense, a tropical epiphytic orchid, to determine if fungal endophytes from the roots of D. sinense were preferentially correlated with host tree species. Fifty-six fungal operational taxonomic units (OTUs) from 36 host trees were identified. The results indicated that the species richness and diversity of mycorrhizal and endophytic fungal communities isolated from D. sinense roots were strongly influenced by host tree species. Both species richness and diversity indices showed that D. sinense roots on Syzygium buxifolium harbored the most diverse and abundant endophytic fungi. Species of Tulasnellaceae were dominant on S. buxifolium and Rhododendron moulmainense but infrequent on Cyclobalanopsis disciformis and Podocarpus neriifolius. Our results provide evidence for distinct mycorrhizal and endophytic fungal communities on different host tree species. Further research focusing on fungi-orchid-host preference could be conducted to increase our understanding for the in situ conservation of epiphytic orchids.

A new cyclopeptide and a new lignan from Podocarpus neriifolius.[Pubmed: 27580458]

A new cyclopeptide, neriitide A (1) and a new lignan, neriilignan (2), along with six known compounds including two diterpenoids, three sesquiterpenoids and one sterol were isolated from the leaves of Podocarpus neriifolius. Their structures were elucidated by means of extensive spectroscopic analysis including HREIMS, 1D and 2D NMR techniques. This is the first report of cyclopeptide and lignan separated from this plant.

An antiproliferative norditerpene dilactone, Nagilactone C, from Podocarpus neriifolius.[Pubmed: 11824527]

An ethanolic extract of Podocarpus neriifolius D. Don (Podocarpaceae) showed antiproliferative activity against two major tumor cell lines, viz. human HT-1080 fibrosarcoma and murine color 26-L5 carcinoma. Bioassay guided fractionation showed the highest antiproliferative activity in chloroform-soluble fraction. Nagilactone C, the major constituent of this fraction was isolated and characterized by using NMR, IR and FAB-MS spectroscopic methods. Nagilactone C possessed potent antiproliferative activity against human fibrosarcoma and murine colon carcinoma tumor cell lines exhibiting ED50 values of 2.3 and 1.2 microg/ml, respectively. Hence, nagilactone C could be the active constituent present in this plant.