Bacterial persistence in the rhizosphere and colonisation of root niches are critical for the establishment of many beneficial plant-bacteria interactions including those between Rhizobium leguminosarum and its host legumes. Despite this, most studies on R. leguminosarum have focused on its symbiotic lifestyle as an endosymbiont in root nodules. Here, we use random barcode transposon sequencing (RB-TnSeq) to assay gene contributions of R. leguminosarum during competitive growth in the rhizosphere and colonisation of various plant species. This facilitated the identification of 189 genes commonly required for growth in diverse plant rhizospheres, mutation of 111 of which also affected subsequent root colonisation (rhizosphere progressive), and a further 119 genes necessary for colonisation. Common determinants reveal a need to synthesise essential compounds (amino acids, ribonucleotides, and cofactors), adapt metabolic function, respond to external stimuli, and withstand various stresses (such as changes in osmolarity). Additionally, chemotaxis and flagella-mediated motility are prerequisites for root colonisation. Many genes showed plant-specific dependencies highlighting significant adaptation to different plant species. This work provides a greater understanding of factors promoting rhizosphere fitness and root colonisation in plant-beneficial bacteria, facilitating their exploitation for agricultural benefit.

中文翻译：

---

根瘤菌根际持久性和根定植的决定因素

根际细菌的持久存在和根生态位的定植对于建立许多有益的植物-细菌相互作用至关重要，包括豆科根瘤菌与其宿主豆科植物之间的相互作用。尽管如此，大多数关于豆角杆菌的研究都集中在其作为根瘤内共生体的共生生活方式。在这里，我们使用随机条形码转座子测序（RB-TnSeq）来测定豆根菌在根际竞争性生长和各种植物物种定殖期间的基因贡献。这有助于鉴定不同植物根际生长通常所需的 189 个基因，其中 111 个基因的突变也影响随后的根定殖（根际渐进），以及另外 119 个定殖所需的基因。常见的决定因素揭示了合成必需化合物（氨基酸、核糖核苷酸和辅因子）、适应代谢功能、响应外部刺激以及承受各种压力（例如渗透压的变化）的需要。此外，趋化性和鞭毛介导的运动是根定植的先决条件。许多基因表现出植物特异性依赖性，突出了对不同植物物种的显着适应。这项工作提供了对促进植物有益细菌根际适应性和根部定殖的因素的更深入的了解，促进了它们的农业效益的利用。