State Key Laboratory of Agrobiotechnology/College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Microb Ecol. 2011 May;61(4):917-31. doi: 10.1007/s00248-011-9820-0. Epub 2011 Feb 22.
A total of 215 rhizobial strains were isolated and analyzed with 16S rRNA gene, 16S-23S intergenic spacer, housekeeping genes atpD, recA, and glnII, and symbiotic genes nifH and nodC to understand the genetic diversity of soybean rhizobia in Hebei province, China. All the strains except one were symbiotic bacteria classified into nine genospecies in the genera of Bradyrhizobium and Sinorhizobium. Surveys on the distribution of these rhizobia in different regions showed that Bradyrhizobium japonicum and Bradyrhizobium elkanii strains were found only in neutral to slightly alkaline soils whereas Bradyrhizobium yuanmingense, Bradyrhizobium liaoningense-related strains and strains of five Sinorhizobium genospecies were found in alkaline-saline soils. Correspondence and canonical correspondence analyses on the relationship of rhizobial distribution and their soil characteristics reveal that high soil pH, electrical conductivity, and potassium content favor distribution of the B. yuanmingense and the five Sinorhizobium species but inhibit B. japonicum and B. elkanii. High contents of available phosphorus and organic matters benefit Sinorhizobium fredii and B. liaoningense-related strains and inhibit the others groups mentioned above. The symbiotic gene (nifH and nodC) lineages among B. elkanii, B. japonicum, B. yuanmingense, and Sinorhizobium spp. were observed in the strains, signifying that vertical gene transfer was the main mechanism to maintain these genes in the soybean rhizobia. However, lateral transfer of symbiotic genes commonly in Sinorhizobium spp. and rarely in Bradyrhizobium spp. was also detected. These results showed the genetic diversity, the biogeography, and the soil determinant factors of soybean rhizobia in Hebei province of China.
共分离和分析了 215 株根瘤菌，使用 16S rRNA 基因、16S-23S 基因间隔区、atpD、recA、glnII 看家基因和 nifH、nodC 共生基因来了解中国河北省大豆根瘤菌的遗传多样性。除一株外，所有菌株均为共生细菌，分为 Bradyrhizobium 和 Sinorhizobium 属的 9 个种。对这些根瘤菌在不同地区分布的调查表明，B. japonicum 和 B. elkanii 菌株仅存在于中性至微碱性土壤中，而 B. yuanmingense、B. liaoningense 相关菌株和 5 个 Sinorhizobium 种的菌株则存在于碱性盐渍土壤中。根瘤菌分布与土壤特性的对应和典范对应分析表明，高土壤 pH 值、电导率和钾含量有利于 B. yuanmingense 和 5 种 Sinorhizobium 种的分布，但抑制了 B. japonicum 和 B. elkanii 的分布。有效磷和有机物含量高有利于 S. fredii 和 B. liaoningense 相关菌株的生长，而抑制了上述其他组的生长。在 B. elkanii、B. japonicum、B. yuanmingense 和 Sinorhizobium spp. 中观察到共生基因（nifH 和 nodC）谱系，表明垂直基因转移是维持大豆根瘤菌中这些基因的主要机制。然而，也检测到了共生基因在 Sinorhizobium spp. 中的水平转移，而在 Bradyrhizobium spp. 中则很少。这些结果显示了中国河北省大豆根瘤菌的遗传多样性、生物地理学和土壤决定因素。
