青藏高原冰川棘豆(Oxytropis glacialis)内生菌核心微生物组的界定及其互作网络分析

Core microflora and endophytic interaction network of Oxytropis glacialis in Qinghai-Tibet Plateau

摘要:

【背景】植物内生菌(endophyte)对寄主植物的益生作用有利于植物的生存与扩散，而菌群互作网络为内生菌生态功能的实现提供了基础保障。【目的】了解影响西藏畜牧业发展的主要疯草冰川棘豆(Oxytropis glacialis)内生菌核心微生物组及其菌群互作网络，为青藏高原疯草类有毒植物的科学治理和利用提供基础参考依据。【方法】利用高通量测序技术分析冰川棘豆中内生菌核心微生物组，构建内生菌相关性网络，并以与苦马豆素代谢相关内生菌为例分析冰川棘豆内生菌的互作模式。【结果】内生细菌测序共得到175 791条有效序列，注释到428个细菌OTU，分属于19个门和267个属；内生真菌测序共得到757 113条有效序列，注释到391个真菌OTU，分属于7个门和149个属。Venn图分析表明，根、叶组织的核心内生细菌菌属数目(54、62)大于核心内生真菌(22、13)，根组织中的核心内生菌种类与叶组织相当(76、75)。系统发育树分析表明，冰川棘豆中存在产生苦马豆素内生真菌链格孢属(Alternaria)和降解苦马豆素的内生细菌短波单胞杆菌属(Brevundimonas)。相关性网络分析表明，内生菌菌群间以正向反馈的互作网络关系为主，核心菌群可能主要通过间接性的互作方式将影响传递到微生物群落，其中链格孢属与短波单胞杆菌属作为核心菌属通过间接性的显著相关关系(|r|>0.6，P<0.01)参与菌群间互作网络。【结论】冰川棘豆核心菌群以间接的方式参与内生菌菌群间的互作网络，高度的菌属连接性为内生菌生态功能的实现提供可能。

Abstract:

[Background] Endophyte is beneficial to host plants for survival and diffusion, and the interaction network of flora provides a basic guarantee for the realization of ecological functions of endophyte. [Objective] To understand the main endophytic microbiota and their interaction network of Oxytropis glacialis that affects the development of animal husbandry in Tibet, so as to provide a reference for the scientific management and utilization of the poisonous plants of locoweed on the Qinghai-Tibet Plateau. [Methods] High-throughput sequencing was used to analyze the endophytic microbiota in the ecotone, to construct the endophytic microbiota correlation network, and to analyze the interaction model of ecotone with the endophytic microbiota related to the metabolism of swainsonine. [Results] A total of 175 791 valid sequences of endophytic bacteria were obtained by sequencing, which annotated to 428 bacterial OTU, belonging to 19 phyla and 267 genera. A total of 757 113 valid sequences of endophytic fungi were obtained, which annotated to 391 fungal OTU, belonging to 7 phylum and 149 genera, Venn diagram analysis showed that the number of endophytic bacteria genus in the core of root and leaf tissues (54, 62) was greater than that of the core endophytic fungi (22, 13), and the core endophytic bacteria species in root tissues were similar to that in leaf tissues (76, 75). Phylogenetic tree analysis showed that Alternaria and Brevundimonas, presenting in Oxytropis glacialis were endophyte that produced and degraded swainsonine. Network analysis showed that the correlation between endogenous bacteria flora was given priority to positive feedback interaction network relationship, the core flora may mainly through indirect interaction modes to affect the microbial community, including Alternaria and Brevundimonas as core species with indirect significant correlation (|r|>0.6, P<0.01) in bacteria interactions within networks. [Conclusion] Oxytropis glacialis core microbiota indirectly participates in the interaction network among endophytes, and the high degree of bacterial connectivity makes it possible to realize the function of endophytes.