ABSTRACT: The health of seagrass plants, and thereby the ecosystems they form, is linked to their associated microbial communities. However, the role of the microbiome in holobiont function and health remains poorly understood for most seagrass species and environmental pressures, and there is, therefore, a need to better understand the drivers behind the formation of and external influences on the seagrass microbiome. Using a core microbiome framework, we characterised the leaf microbiomes of 6 estuarine seagrass populations after a precipitation event to explore how the microbiomes vary across different sites and salinities over a regional spatial scale. We found that each estuary had distinct core bacterial community structures (beta-diversity), but shared a more similar fungal core community structure. We hypothesise that the differences in the bacterial members of the microbiomes among estuaries are generally the result of each estuary being influenced by unique watersheds and sources of prokaryotes. In contrast, the similarity in the core fungal communities suggests that the eukaryotic components of the microbiomes are likely under selection or result from similar colonisation pathway(s). We also found that the bacterial taxa driving the differences among estuaries were linked to the salinity of the estuary, likely due to (1) the general epibiotic nature of colonisation (i.e. watershed source and exposure) and (2) members or functional groups within the leaf microbiome assisting seagrasses in coping with the extreme salinities. These results are valuable for linking microbiomes to the resilience of seagrasses living within dynamic estuaries experiencing a range of physicochemical pressures.

中文翻译：

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河口海草叶微生物群细菌和真菌群落的空间变异

摘要：海草植物的健康及其形成的生态系统与其相关的微生物群落有关。但是，对于大多数海草种类和环境压力，微生物组在全生命周期功能和健康中的作用仍然知之甚少，因此，需要更好地了解海草微生物组形成和外部影响的驱动因素。使用核心的微生物组框架，我们对6个河口海草种群的叶片微生物组进行了降水事件表征，以探讨该微生物组在区域空间尺度上不同地点和盐度之间如何变化。我们发现，每个河口都有独特的核心细菌群落结构（β-多样性），但共有更相似的真菌核心群落结构。我们假设河口之间的微生物群细菌成员的差异通常是每个河口受独特的分水岭和原核生物来源影响的结果。相反，核心真菌群落中的相似性表明，微生物组的真核生物组分很可能处于选择之下或源自相似的定殖途径。我们还发现，驱动河口差异的细菌类群与河口盐度有关，这可能是由于（1）殖民化的一般表生性（即分水岭的来源和暴露程度）和（2）河口内的成员或功能组叶片微生物组可帮助海草应对极高的盐度。