title: Genotypic alteration and competitive nodulation of Mesorhizobium muleiense against exotic chickpea rhizobia in alkaline soils.
abstract: Mesorhizobium muleiense, Mesorhizobium mediterraneum and Mesorhizobium ciceri are chickpea (Cicer arietinum L.) rhizobia that share a high similarity of the symbiotic genes nodC and nifH, but they have different geographic distributions. M. muleiense has been isolated and found only in alkaline soils of Xinjiang, China, whereas the other two strains have been found in the Mediterranean and India. To investigate the species stability of M. muleiense during natural evolution and its capability of competitive nodulation against the other two exotic species, re-sampling of nodules in the field and competition experiments between the three species were conducted. The results showed that the predominant microsymbiont associated with chickpea grown in Xinjiang was still M. muleiense, but the predominant genotypes of M. muleiense had changed significantly during the four years since a previous survey. The data also showed that M. mediterraneum and M. ciceri were more competitive than the residential strain of M. muleiense CCBAU 83963(T) in sterilized vermiculite or soils from Xinjiang. However, in non-sterilized soils, M. muleiense was the predominant nodule occupier. These results indicated that natural or adapting evolution of M. muleiense was occurring in fields subjected to changing environmental factors. In addition, the biogeography and symbiotic associations of rhizobia with their host legumes were also influenced by biological factors in the soil, such as indigenous rhizobia and other organisms.
authors.affiliation: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Jun Jie
authors.initials: JJ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.affiliation: Institute of Microbiology, Xinjiang Academy of Agricultural Science, Urumqi 830091, Xinjiang, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Lou
authors.affiliation: Laboratory of Ion Beam Biotechnology, College of Physics Science and Technology, Xinjiang University, Urumqi 830008, Xinjiang, China.
authors.forename: Pei Hong
authors.initials: PH
authors.lastname: Mao
authors.affiliation: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China; Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, 11340 México, D.F., Mexico.
authors.forename: En Tao
authors.initials: ET
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China. Electronic address: chenwf@cau.edu.cn.
authors.forename: Wen Feng
authors.initials: WF
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Wen Xin
authors.initials: WX
authors.lastname: Chen
mesh_terms: D002681:China; D029863:Cicer / Q000382:microbiology*; D004269:DNA, Bacterial; D017753:Ecosystem; D059128:Mesorhizobium / Q000235:genetics* / Q000254:growth & development*; D008969:Molecular Sequence Data; D055170:Plant Root Nodulation; D053204:Root Nodules, Plant / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D004269:DNA, Bacterial; D012987:Soil
keywords: Chickpea; Competitive nodulation; Genotype; Mesorhizobium ciceri; Mesorhizobium mediterraneum; Mesorhizobium muleiense