Verástegui-Valdés Myrthala M, Zhang Yu Jing, Rivera-Orduña Flor N, Cheng Hai-Ping, Sui Xing Hua, Wang En Tao
Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, C.P. 11430, Mexico, D.F., Mexico.
State Key Laboratory of Agrobiotechnology and Center of Biomass Engineering, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Syst Appl Microbiol. 2014 Dec;37(8):605-12. doi: 10.1016/j.syapm.2014.08.005. Epub 2014 Sep 28.
In order to investigate bean-nodulating rhizobia in different types of soil, 41 nodule isolates from acid and alkaline soils in Mexico were characterized. Based upon the phylogenetic studies of 16S rRNA, atpD, glnII, recA, rpoB, gyrB, nifH and nodC genes, the isolates originating from acid soils were identified as the phaseoli symbiovar of the Rhizobium leguminosarum-like group and Rhizobium grahamii, whereas the isolates from alkaline soils were defined as Ensifer americanum sv. mediterranense and Rhizobium radiobacter. The isolates of "R. leguminosarum" and E. americanum harbored nodC and nifH genes, but the symbiotic genes were not detected in the four isolates of the other two species. It was the first time that "R. leguminosarum" and E. americanum have been reported as bean-nodulating bacteria in Mexico. The high similarity of symbiotic genes in the Rhizobium and Ensifer populations showed that these genes had the same origin and have diversified recently in different rhizobial species. Phenotypic characterization revealed that the "R. leguminosarum" population was more adapted to the acid and low salinity conditions, while the E. americanum population preferred alkaline conditions. The findings of this study have improved the knowledge of the diversity, geographic distribution and evolution of bean-nodulating rhizobia in Mexico.
为了研究不同类型土壤中的豆类根瘤菌，对来自墨西哥酸性和碱性土壤的41株根瘤分离株进行了表征。基于16S rRNA、atpD、glnII、recA、rpoB、gyrB、nifH和nodC基因的系统发育研究，源自酸性土壤的分离株被鉴定为类豆科根瘤菌组的菜豆共生变种和格雷厄姆根瘤菌，而来自碱性土壤的分离株被定义为地中海美国剑菌和放射形根瘤菌。“豆科根瘤菌”和美国剑菌的分离株含有nodC和nifH基因，但在其他两个物种的四个分离株中未检测到共生基因。这是首次在墨西哥报道“豆科根瘤菌”和美国剑菌为豆类结瘤细菌。根瘤菌和剑菌群体中共生基因的高度相似性表明，这些基因起源相同，最近在不同的根瘤菌物种中发生了分化。表型特征表明，“豆科根瘤菌”群体更适应酸性和低盐度条件，而美国剑菌群体更喜欢碱性条件。本研究的结果提高了对墨西哥豆类根瘤菌的多样性、地理分布和进化的认识。
