[Effects of germplasm and host tree trunk on endophytic fungal communities in epiphytic Dendrobium catenatum].

In order to investigate the effects of germplasm and host tree trunk on endophytic fungal communities in epiphytic Dendrobium catenatum, a total of 3 835 isolates were recovered from roots, stems and leaves of four D. catenatum germplasms attached to one kind of host tree trunk and one germplasm attached to four kinds of epiphyte-host tree trunks. A total of 152 taxa were identified and classified based on the fungal cultural characteristics and phylogenetic analyses of ITS sequences. The taxa were assigned to 60 genera, 35 families, 21 orders and 5 classes of 2 phyla. The results indicated that D. catenatum cultivated in stereo cultivation harbor variety of fungi. The dominant fungal groups were different between Lin'an and Yiwu. Moreover, several groups showed geographical specificity, such as Arthrinium, Coniochaeta, Fusarium, Neofusicoccum and Zopfiella only dominating in Panshan of Lin'an, while Alternaria, Bjerkandera, Cercophora, Nigrospora and Trichoderma only dominating in Shangxi of Yiwu. There was no significant difference in diversity or species richness of endophytic fungi neither among germplasm nor host tree trunk. However, the richness and diversity indices exhibited a strong dependence on tissue type (P<0.05). The germplasm and host tree trunk impact the distribution patterns of endophytic fungi less than tissue type. Nevertheless, the relative frequencies of the dominant fungal groups were different among germplasms or host tree trunk types. Furthermore, there were some fungal species specific to certain germplasm or host tree trunk. This might be due to the distinctions in growth traits and chemical compositions of D. catenatum owning to the differences in D. catenatumgenetic background and microenvironment of host tree. Most of fungal taxa exhibit tissue specificity or preference. These results provide the basis for the study on the relationship between endophytic fungi and D. catenatum in stereo cultivation mode.

Cytotoxic and Antifungal Constituents Isolated from the Metabolites of Endophytic Fungus DO14 from Dendrobium officinale.

Two novel cytotoxic and antifungal constituents, (4S,6S)-6-[(1S,2R)-1, 2-dihydroxybutyl]-4-hydroxy-4-methoxytetrahydro-2H-pyran-2-one (1), (6S,2E)-6-hydroxy-3-methoxy-5-oxodec-2-enoic acid (2), together with three known compounds, LL-P880γ (3), LL-P880α (4), and Ergosta-5,7,22-trien-3b-ol (5) were isolated from the metabolites of endophytic fungi from Dendrobium officinale. The chemical structures were determined based on spectroscopic methods. All the isolated compounds 1-5 were evaluated by cytotoxicity and antifungal effects. Our present results indicated that compounds 1-4 showed notable anti-fungal activities (minimal inhibitory concentration (MIC) ≤ 50 µg/mL) for all the tested pathogens including Candida albicans, Cryptococcus neoformans, Trichophyton rubrum, Aspergillus fumigatus. In addition, compounds 1-4 possessed notable cytotoxcities against human cancer cell lines of HL-60 cells with the IC50 values of below 100 µM. Besides, compounds 1, 2, 4 and 5 showed strong cytotoxities on the LOVO cell line with the IC50 values were lower than 100 µM. In conclusion, our study suggested that endophytic fungi of D. officinale are great potential resources to discover novel agents for preventing or treating pathogens and tumors.

[Dendrobium officinale stereoscopic cultivation method].

The study is aimed to make the most of available space of Dendrobium officinale cultivation facility, reveal the yield and functional components variation of stereoscopic cultivated D. officinale, and improve quality, yield and efficiency. The agronomic traits and yield variation of stereoscopic cultivated D. officinale were studied by operating field experiment. The content of polysaccharide and extractum were determined by using phenol-sulfuric acid method and 2010 edition of "Chinese Pharmacopoeia" Appendix X A. The results showed that the land utilization of stereoscopic cultivated D. officinale increased 2.74 times, the stems, leaves and their total fresh or dry weight in unit area of stereoscopic cultivated D. officinale were all heavier than those of the ground cultivated ones. There was no significant difference in polysaccharide content between stereoscopic cultivation and ground cultivation. But the extractum content and total content of polysaccharide and extractum were significantly higher than those of the ground cultivated ones. In additional, the polysaccharide content and total content of polysaccharide and extractum from the top two levels of stereoscopic culture matrix were significantly higher than that of the ones from the other levels and ground cultivation. Steroscopic cultivation can effectively improves the utilization of space and yield, while the total content of polysaccharides and extractum were significantly higher than that of the ground cultivated ones. The significant difference in Dendrobium polysaccharides among the plants from different height of stereo- scopic culture matrix may be associated with light factor.