The active bacterial rhizobiomes and root exudate profiles of phytometers of six plant species growing in central European temperate grassland communities were investigated in three regions located up to 700 km apart, across diverse edaphic conditions and along a strong land use gradient. The recruitment process from bulk soil communities was identified as the major direct driver of the composition of active rhizosphere bacterial communities. Unexpectedly, the effect of soil properties, particularly soil texture, water content, and soil type, strongly dominated over plant properties and the composition of polar root exudates of the primary metabolism. While plant species-specific selection of bacteria was minor, the RNA-based composition of active rhizosphere bacteria substantially differed between rhizosphere and bulk soil. Although other variables could additionally be responsible for the consistent enrichment of particular bacteria in the rhizosphere, distinct bacterial OTUs were linked to the presence of specific polar root exudates independent of individual plant species. Our study also identified numerous previously unknown taxa that are correlated with rhizosphere dynamics and hence represent suitable targets for future manipulations of the plant rhizobiome.

中文翻译：

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温带草原活跃根际细菌群落组成的驱动因素。

在相距达 700 公里的三个区域、不同的土壤条件和强烈的土地利用梯度下，研究了生长在中欧温带草原群落的六种植物物种的活性细菌根茎生物群落和根系分泌物谱。来自大块土壤群落的补充过程被确定为活性根际细菌群落组成的主要直接驱动因素。出乎意料的是，土壤特性的影响，特别是土壤质地、含水量和土壤类型，强烈地支配了植物特性和初级代谢的极根分泌物的组成。虽然对细菌的植物物种特异性选择很少，但根际和大块土壤之间基于 RNA 的活性根际细菌组成存在显着差异。尽管其他变量也可能导致根际特定细菌的持续富集，但不同的细菌 OTU 与特定极根分泌物的存在有关，而与单个植物物种无关。我们的研究还确定了许多以前未知的与根际动态相关的分类群，因此代表了未来操纵植物根际生物群落的合适目标。