Microbial inoculation has been proposed as a potential approach for rhizosphere engineering. However, it is still unclear to what extent successful plant growth-promoting effects are driven by the origin of the microbial inocula and which taxa are responsible for the plant-beneficial effects. We conducted a microbial transplant experiment by using different microbial inocula (and nutrient controls) isolated from forest, soybean and tomato field soils and determined their effects on tomato plant biomass and nutrient assimilation in sterilized tomato soil. Rhizosphere bacterial communities were compared at the end of the experiment and correlative and machine learning analyses used to identify potential keystone taxa associated with the plant growth-promotion. Microbial inoculants had a clear positive effect on plant growth compared to control nutrient inoculants. Specifically, positive effects on the plant biomass were significantly associated with microbial inoculants from the forest and soybean field soils, while microbial inoculants from the forest and tomato field soils had clear positive effects on the plant nutrient assimilation. Soil nutrients alone had relatively minor effects on rhizosphere bacterial communities. However, the origin of microbial inoculants had clear effects on the structure of bacterial community structure with tomato and soybean inoculants having positive effects on the diversity and abundance of bacterial communities, respectively. Specifically, Streptomyces, Luteimonas and Enterobacter were identified as the potential keystone genera affecting plant growth. The origin of soil microbiome inoculant can predictably influence plant growth and nutrient assimilation and that these effects are associated with certain key bacterial genera.

中文翻译：

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菌剂来源对根际细菌群落组成及植物生长促进作用的研究

微生物接种已被提议作为根际工程的潜在方法。然而，目前尚不清楚微生物接种物的来源在多大程度上成功地促进了植物生长，以及哪些分类群对植物有益。我们使用从森林、大豆和番茄田间土壤中分离出的不同微生物接种物（和养分对照）进行了微生物移植实验，并确定了它们对灭菌番茄土壤中番茄植物生物量和养分同化的影响。在实验结束时比较了根际细菌群落，并使用相关和机器学习分析来识别与植物生长促进相关的潜在关键分类群。与对照营养接种剂相比，微生物接种剂对植物生长具有明显的积极影响。具体而言，对植物生物量的积极影响与来自森林和大豆田土壤的微生物菌剂显着相关，而来自森林和番茄田土壤的微生物菌剂对植物养分同化具有明显的积极影响。仅土壤养分对根际细菌群落的影响相对较小。然而，微生物接种剂的来源对细菌群落结构的结构有明显影响，番茄和大豆接种剂分别对细菌群落的多样性和丰度产生积极影响。具体而言，链霉菌属、黄体单胞菌属和肠杆菌属被确定为影响植物生长的潜在关键属。