Guangxi Zhiwu (Jun 2023)
Diversity study of endophytic communities in fresh and silica gel-dried root samples of Holcoglossum kimballianum (Orchidaceae)
Abstract
Holcoglossum kimballianum is a rare and endangered orchid, and its wild populations are in urgent need of conservation. Endophytic fungi and bacteria are important to the growth and development of orchids. In order to assess the diversity of H. kimballianum endophytes and the impact of sampling methods on the endophytes, high-throughput sequencing technology was used to study the diversity of endophytes in fresh and silica gel-dried roots of H. kimballianum in ex-situ conservation. The results were as follows: (1) The species compositions of endophytic fungi and endophytic bacteria were distinctly different in fresh and silica gel-dried roots of H. kimballianum. There were total of 6 phyla 46 families 51 genera of endophytic fungi and 15 phyla 105 families 178 genera of endophytic bacteria annotated in the roots of the H. kimballianum. After silica gel-dried, the endophytic fungi of the H. kimballianum had total of 6 phyla, 88 families, 116 genera, and the endophytic bacteria had total of 21 phyla, 154 families, 336 genera. (2) Endophytes in the roots of H. kimballianum in ex-situ conservation were of richness and diversity of endophytic bacterial community was much higher than that of endophytic fungal community. After silica gel-dried, the α diversity indices of endophytic fungi increased and the β diversity indices decreased, while the α diversity indices of endophytic bacteria decreased and the β diversity indices increased. (3) Significantly different fungi Psathyrella candolleana and Colletotrichum tofieldiae only existed in the endophytic fungal communities of fresh roots. The significantly different bacteria in roots of fresh Hocoglossum kimballianum was Marseilla, and the significantly different bacteria in the silica gel-dried roots included Beijerinckiaceae, Xanthobacteraceae and Bradyrhizobium. (4) Co-occurrence network analysis revealed that the dominant species and interaction patterns in the endophytic communities of the roots of Hocoglossum kimballianum were changed after silica gel-dried. In summary, different sampling treatments can affect the community structure of the endophytes in the roots of H. kimballianum, and it is advisable to use fresh root samples when studying the endophytes of orchids. The results provide an endophytic data basis for wild populations conservation and artificial cultivation of H. kimballianum, and also provide a reference for sampling methods of endophytic microorganisms in orchids.
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