title: Microsymbionts of Phaseolus vulgaris in acid and alkaline soils of Mexico.
abstract: 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.
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, C.P. 11430, Mexico, D.F., Mexico.
authors.forename: Myrthala M
authors.initials: MM
authors.lastname: Verástegui-Valdés
authors.affiliation: State Key Laboratory of Agrobiotechnology and Center of Biomass Engineering, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Yu Jing
authors.initials: YJ
authors.lastname: Zhang
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, C.P. 11430, Mexico, D.F., Mexico.
authors.forename: Flor N
authors.initials: FN
authors.lastname: Rivera-Orduña
authors.affiliation: Biological Sciences Department, Lehman College and Graduate Center, The City University of New York, Bronx, NY, USA.
authors.forename: Hai-Ping
authors.initials: HP
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Agrobiotechnology and Center of Biomass Engineering, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Xing Hua
authors.initials: XH
authors.lastname: Sui
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, C.P. 11430, Mexico, D.F., Mexico. Electronic address: ewang@encb.ipn.mx.
authors.forename: En Tao
authors.initials: ET
authors.lastname: Wang
mesh_terms: D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008800:Mexico; D008969:Molecular Sequence Data; D027805:Phaseolus / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012231:Rhizobium / Q000145:classification / Q000235:genetics / Q000502:physiology; D053204:Root Nodules, Plant / Q000382:microbiology; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012987:Soil
keywords: Biogeography; Mobility; Phaseolus; Phylogeny; Rhizobia; Soil pH