Genotypic alteration and competitive nodulation of Mesorhizobium muleiense against exotic chickpea rhizobia in alkaline soils.
Jun Jie Zhang, Tao Yu, Kai Lou, Pei Hong Mao, En Tao Wang, Wen Feng Chen, Wen Xin Chen
Author Information
Jun Jie Zhang: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Tao Yu: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China.
Kai Lou: Institute of Microbiology, Xinjiang Academy of Agricultural Science, Urumqi 830091, Xinjiang, China.
Pei Hong Mao: Laboratory of Ion Beam Biotechnology, College of Physics Science and Technology, Xinjiang University, Urumqi 830008, Xinjiang, China.
En Tao Wang: 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.
Wen Feng Chen: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China. Electronic address: chenwf@cau.edu.cn.
Wen Xin Chen: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China.
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.
