管叶槽舌兰新鲜及硅胶干燥根样内生菌多样性研究

Diversity study of endophytic communities in fresh and silica gel-dried root samples of Holcoglossum kimballianum(Orchidaceae)

关键词:  管叶槽舌兰, 内生真菌, 内生细菌, 新鲜, 硅胶干燥, 多样性

Key words:  Holcoglossum kimballianum, endophytic fungi, endophytic bacteria, fresh, silica gel-dried, diversity

摘要:

管叶槽舌兰(Holcoglossum kimballianum)是一种珍稀濒危兰科植物,其野生种群亟需保护。内生菌对兰科植物的生长发育至关重要,为评估管叶槽舌兰内生菌的多样性、分析采样方式对其内生菌的影响,该文采用高通量测序技术对迁地保育状态下新鲜与硅胶干燥的管叶槽舌兰根内生菌进行研究。结果表明:(1)新鲜及干燥管叶槽舌兰根内生菌物种组成明显不同,管叶槽舌兰内生真菌注释到6门46科51属,内生细菌注释到15门105科178属; 干燥后管叶槽舌兰根内生真菌注释到6门88科116属,内生细菌注释到21门154科336属。(2)迁地保育状态的管叶槽舌兰根样内生菌具有丰富的多样性,并且内生细菌群落丰富度和多样性远比内生真菌群落高; 经硅胶干燥后,内生真菌α多样性指数升高、β多样性指数降低,而内生细菌的α多样性指数降低、β多样性指数则升高。(3)差异显著性真菌黄盖小脆柄菇(Psathyrella candolleana)和刺盘孢属(Colletotrichum)的C. tofieldiae只存在于新鲜根样中,新鲜管叶槽舌兰差异显著性细菌是马赛菌属(Massilia),干燥根样中差异显著性细菌类群包括拜叶林克氏菌科(Beijerinckiaceae)、黄色杆菌科(Xanthobacteraceae)及慢生根瘤菌属(Bradyrhizobium)。(4)共发生网络分析显示,经干燥后管叶槽舌兰根样内生菌群落中占互作主导地位的优势物种和互作模式都发生了改变。综上认为,不同采样处理会影响管叶槽舌兰根内生菌的群落结构,在研究兰科植物根样内生菌时宜使用新鲜的根样。该研究结果为管叶槽舌兰野生种群保护及人工栽培提供了内生菌数据基础,也为兰科植物内生微生物采样方法提供了参考。

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.