Rhizobia-legume symbiosis is an important type of plant-microbe mutualism; however, the establishment of this association is complicated and can be affected by many factors. The soybean rhizosphere has a specific microbial community, yet whether these organisms affect rhizobial nodulation has not been well investigated. Here, we analyzed the compositions and relationships of soybean rhizocompartment microbiota in three types of soil. First, we found that the rhizosphere community composition of soybean varied significantly in different soils, and the association network between rhizobia and other rhizosphere bacteria was examined. Second, we found that some rhizosphere microbes were correlated with the composition of bradyrhizobia and sinorhizobia in nodules. We cultivated 278 candidate Bacillus isolates from alkaline soil. Finally, interaction and nodulation assays showed that the Bacillus cereus group specifically promotes and suppresses the growth of sinorhizobia and bradyrhizobia, respectively, and alleviates the effects of saline-alkali conditions on the nodulation of sinorhizobia as well as affecting its colonization in nodules. Our findings demonstrate a crucial role of the bacterial microbiota in shaping rhizobia-host interactions in soybean, and provide a framework for improving the symbiotic efficiency of this system of mutualism through the use of synthetic bacterial communities.

中文翻译：

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大豆根际微生物群落的变化及其与根瘤菌共生效率的关系。

根瘤菌-豆类共生是植物-微生物共生的一种重要类型。但是，这种关联的建立很复杂，并可能受到许多因素的影响。大豆根际层具有特定的微生物群落，但尚未充分研究这些生物是否影响根瘤结节。在这里，我们分析了三种类型土壤中大豆根际区隔微生物群的组成和相互关系。首先，我们发现大豆的根际群落组成在不同的土壤中有显着差异，并检查了根际细菌与其他根际细菌之间的联系网络。其次，我们发现一些根际微生物与结节中的缓生根瘤菌和少生根瘤菌的成分有关。我们从碱性土壤中培养了278个候选芽孢杆菌分离株。最后，相互作用和结瘤试验表明蜡状芽孢杆菌组分别特异性地促进和抑制了鼻窦菌和迟发性根瘤菌的生长，并减轻了盐碱条件对鼻窦菌的结节的影响，并影响了其在结节中的定殖。我们的发现证明了细菌微生物群在塑造大豆根瘤菌-宿主相互作用中的关键作用，并为通过使用合成细菌群落提高这种共生系统的共生效率提供了框架。并减轻了盐碱条件对鼻窦瘤的结节的影响以及影响其在结节中的定殖。我们的发现证明了细菌微生物群在塑造大豆根瘤菌-宿主相互作用中的关键作用，并为通过使用合成细菌群落提高这种共生系统的共生效率提供了框架。并且减轻了盐碱条件对鼻窦菌根瘤的影响以及影响其在结节中的定殖。我们的发现证明了细菌微生物群在塑造大豆根瘤菌-宿主相互作用中的关键作用，并为通过使用合成细菌群落提高这种共生系统的共生效率提供了框架。