Department of Crop Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
Sci Rep. 2023 Oct 9;13(1):17029. doi: 10.1038/s41598-023-43634-5.
In most legumes, the rhizobial symbionts exhibit diversity across different environments. Although common bean (Phaseolus vulgaris L.) is one of the important legumes in southern Africa, there is no available information on the genetic diversity and N-fixing effectiveness of its symbionts in Malkerns, Eswatini. In this study, we assessed the phylogenetic positions of rhizobial microsymbionts of common bean from Malkerns in Eswatini. The isolates obtained showed differences in morpho-physiology and N-fixing efficiency. A dendrogram constructed from the ERIC-PCR banding patterns, grouped a total of 88 tested isolates into 80 ERIC-PCR types if considered at a 70% similarity cut-off point. Multilocus sequence analysis using 16S rRNA, rpoB, dnaK, gyrB, and glnII and symbiotic (nifH and nodC) gene sequences closely aligned the test isolates to the type strains of Rhizobium muluonense, R. paranaense, R. pusense, R. phaseoli and R. etli. Subjecting the isolates in this study to further description can potentially reveal novel species. Most of the isolates tested were efficient in fixing nitrogen and elicited greater stomatal conductance and photosynthetic rates in the common bean. Relative effectiveness (RE) varied from 18 to 433%, with 75 (85%) out of the 88 tested isolates being more effective than the nitrate fed control plants.
在大多数豆科植物中，根瘤菌共生体在不同环境中表现出多样性。虽然普通菜豆（Phaseolus vulgaris L.）是南非的重要豆科植物之一，但在斯威士兰的马尔克恩斯地区，其共生体的遗传多样性和固氮效率尚无可用信息。在这项研究中，我们评估了斯威士兰马尔克恩斯地区普通菜豆根瘤菌微共生体的系统发育地位。获得的分离株在形态生理学和固氮效率方面表现出差异。基于 ERIC-PCR 带型构建的系统发育树，在考虑 70%相似性截断值的情况下，将总共 88 个测试分离株分为 80 个 ERIC-PCR 型。使用 16S rRNA、rpoB、dnaK、gyrB 和 glnII 以及共生（nifH 和 nodC）基因序列的多位点序列分析，将测试分离株与 Rhizobium muluonense、R. paranaense、R. pusense、R. phaseoli 和 R. etli 的模式菌株紧密对齐。对本研究中的分离株进行进一步描述可能会揭示新的物种。测试的大多数分离株在固氮方面效率很高，并在普通菜豆中引起更大的气孔导度和光合速率。相对有效性（RE）从 18%到 433%不等，88 个测试分离株中有 75 个（85%）比施硝酸盐的对照植物更有效。
