دورية
Evolutionary origin and ecological implication of a unique nifisland in free-living Bradyrhizobiumlineages
| العنوان: | Evolutionary origin and ecological implication of a unique nifisland in free-living Bradyrhizobiumlineages |
|---|---|
| المؤلفون: | Tao, Jinjin, Wang, Sishuo, Liao, Tianhua, Luo, Haiwei |
| المصدر: | The ISME Journal; November 2021, Vol. 15 Issue: 11 p3195-3206, 12p |
| مستخلص: | The alphaproteobacterial genus Bradyrhizobiumhas been best known as N2-fixing members that nodulate legumes, supported by the nifand nodgene clusters. Recent environmental surveys show that Bradyrhizobiumrepresents one of the most abundant free-living bacterial lineages in the world’s soils. However, our understanding of Bradyrhizobiumcomes largely from symbiotic members, biasing the current knowledge of their ecology and evolution. Here, we report the genomes of 88 Bradyrhizobiumstrains derived from diverse soil samples, including both nif-carrying and non-nif-carrying free-living (nodfree) members. Phylogenomic analyses of these and 252 publicly available Bradyrhizobiumgenomes indicate that nif-carrying free-living members independently evolved from symbiotic ancestors (carrying both nifand nod) multiple times. Intriguingly, the nifphylogeny shows that the vast majority of nif-carrying free-living members comprise an independent cluster, indicating that horizontal gene transfer promotes nifexpansion among the free-living Bradyrhizobium. Comparative genomics analysis identifies that the nifgenes found in free-living Bradyrhizobiumare located on a unique genomic island of ~50?kb equipped with genes potentially involved in coping with oxygen tension. We further analyze amplicon sequencing data to show that Bradyrhizobiummembers presumably carrying this nifisland are widespread in a variety of environments. Given the dominance of Bradyrhizobiumin world’s soils, our findings have implications for global nitrogen cycles and agricultural research. |
| قاعدة البيانات: | Supplemental Index |
Find this article in full text from Springer Verlag. 
Full Text Finder | تدمد: | 17517362 17517370 |
|---|---|
| DOI: | 10.1038/s41396-021-01002-z |