Plant-associated bacterial assemblages are critical for plant fitness. Thus, identifying a consistent plant-associated core microbiome is important for predicting community responses to environmental changes. Our target was to identify the core bacterial microbiome of orchard grass Dactylis glomerata L. and to assess the part that is most sensitive to land management. Dactylis glomerata L. samples were collected from grassland sites with contrasting land use intensities but comparable soil properties at three different timepoints. To assess the plant-associated bacterial community structure in the compartments rhizosphere, bulk soil and endosphere, a molecular barcoding approach based on high throughput 16S rRNA amplicon sequencing was used. A distinct composition of plant-associated core bacterial communities independent of land use intensity was identified. Pseudomonas, Rhizobium and Bradyrhizobium were ubiquitously found in the root bacterial core microbiome. In the rhizosphere, the majority of assigned genera were Rhodoplanes, Methylibium, Kaistobacter and Bradyrhizobium. Due to the frequent occurrence of plant-promoting abilities in the genera found in the plant-associated core bacterial communities, our study helps to identify “healthy” plant-associated bacterial core communities. The variable part of the plant-associated microbiome, represented by the fluctuation of taxa at the different sampling timepoints, was increased under low land use intensity. This higher compositional variation in samples from plots with low land use intensity indicates a more selective recruitment of bacteria with traits required at different timepoints of plant development compared to samples from plots with high land use intensity.

中文翻译：

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不同土地利用强度下土壤中生长的小根实蝇不同根室的核心细菌分类群的定义

与植物相关的细菌组合对于植物适应性至关重要。因此，确定一致的植物相关核心微生物组对于预测社区对环境变化的反应非常重要。我们的目标是确定果园草Dactylis glomerata L.的核心细菌微生物组，并评估对土地管理最敏感的部分。小球藻L.样品是从草地场采集的，具有不同的土地利用强度，但在三个不同的时间点具有可比的土壤特性。为了评估根际，大块土壤和内层空间中与植物相关的细菌群落结构，使用了基于高通量16S rRNA扩增子测序的分子条形码方法。确定了与土地利用强度无关的植物相关核心细菌群落的独特组成。假单胞菌，根瘤菌和根瘤菌根细菌微生物的核心是中无所不在。在根际，大多数分配的属人Rhodoplanes，Methylibium，Kaistobacter和缓生根瘤菌。由于在与植物相关的核心细菌群落中发现的属中植物促进能力的频繁发生，因此我们的研究有助于鉴定“健康”的与植物相关的细菌核心群落。在低土地利用强度下，植物相关微生物组的可变部分以不同采样时间点的分类单元的波动为代表。与土地利用强度高的样地相比，土地利用强度低的样地中样品的这种较高的成分变化表明，在植物发育的不同时间点具有所需性状的细菌更具选择性地募集。