Nitrogen fixing symbiosis between rhizobia and legumes contributes significant amounts of N to agricultural and natural environments. In natural soils, rhizobia compete with indigenous bacterial communities to colonize legume roots, which leads to symbiotic interactions. However, limited information is currently available on the effects of the rhizobial symbiont on the resident microbial community in the legume rhizosphere, rhizoplane, and endosphere, which is partly due to the presence of native nodulating rhizobial strains. In the present study, we used a symbiotic system comprised of Paraburkholderia phymatum and Mimosa pudica to examine the interaction of an inoculant strain with indigenous soil bacteria. The effects of a symbiont inoculation on the native bacterial community was investigated using high throughput sequencing and an analysis of 16S rRNA gene amplicons. The results obtained revealed that the inoculation induced significant alterations in the microbial community present in the rhizoplane+endosphere of the roots, with 13 different taxa showing significant changes in abundance. No significant changes were observed in the rhizospheric soil. The relative abundance of P. phymatum significantly increased in the rhizoplane+endosphere of the root, but significant decreased in the rhizospheric soil. While the rhizosphere, rhizoplane, and root endosphere contained a wide diversity of bacteria, the nodules were predominantly colonized by P. phymatum. A network analysis revealed that the operational taxonomic units of Streptomyces and Phycicoccus were positively associated with P. phymatum as potential keystone taxa. Collectively, these results suggest that the success of an inoculated symbiont depends on its ability to colonize the roots in the face of competition by other soil bacteria. A more detailed understanding of the mechanisms by which an inoculated strain colonizes its plant host is crucial for realizing the full potential of microbial inoculants in sustainable agriculture.

中文翻译：

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用 Paraburkholderia phymatum 接种含羞草导致根际微生物群落结构发生变化。

根瘤菌和豆类之间的固氮共生为农业和自然环境贡献了大量的氮。在天然土壤中，根瘤菌与本土细菌群落竞争以在豆科植物根部定植，从而导致共生相互作用。然而，目前关于根瘤菌共生体对豆科植物根际、根际和内圈中常驻微生物群落的影响的信息有限，部分原因是天然根瘤菌菌株的存在。在本研究中，我们使用由 Paraburkholderia phymatum 和 Mimosa pudica 组成的共生系统来检查接种菌株与本地土壤细菌的相互作用。使用高通量测序和 16S rRNA 基因扩增子分析研究了共生体接种对天然细菌群落的影响。获得的结果表明，接种导致根的根际 + 内圈中存在的微生物群落发生显着变化，13 个不同的分类群显示出显着的丰度变化。在根际土壤中没有观察到显着变化。P. phymatum的相对丰度在根的根际+内圈显着增加，而在根际土壤中显着减少。虽然根际、根面和根内圈含有多种细菌，但根瘤主要由 P. phymatum 定殖。网络分析显示，链霉菌属和藻球菌属的操作分类单元与 P. phymatum 作为潜在的关键分类群呈正相关。总的来说，这些结果表明，接种共生体的成功取决于其在面对其他土壤细菌的竞争时定植根部的能力。更详细地了解接种菌株在其植物宿主中定殖的机制对于实现微生物接种剂在可持续农业中的全部潜力至关重要。