title: Abundance and diversity of soybean-nodulating rhizobia in black soil are impacted by land use and crop management.
abstract: To investigate the effects of land use and crop management on soybean rhizobial communities, 280 nodule isolates were trapped from 7 fields with different land use and culture histories. Besides the known Bradyrhizobium japonicum, three novel genospecies were isolated from these fields. Grassland (GL) maintained a higher diversity of soybean bradyrhizobia than the other cultivation systems. Two genospecies (Bradyrhizobium spp. I and III) were distributed widely in all treatments, while Bradyrhizobium sp. II was found only in GL treatment. Cultivation with soybeans increased the rhizobial abundance and diversity, except for the soybean monoculture (S-S) treatment. In monoculture systems, soybeans favored Bradyrhizobium sp. I, while maize and wheat favored Bradyrhizobium sp. III. Fertilization decreased the rhizobial diversity indexes but did not change the species composition. The organic carbon (OC) and available phosphorus (AP) contents and pH were the main soil parameters positively correlated with the distribution of Bradyrhizobium spp. I and II and Bradyrhizobium japonicum and negatively correlated with Bradyrhizobium sp. III. These results revealed that different land uses and crop management could not only alter the diversity and abundance of soybean rhizobia, but also change interactions between rhizobia and legume or nonlegume plants, which offered novel information about the biogeography of rhizobia.
authors.affiliation: Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yan
authors.affiliation: Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, China xzhan@neigaehrb.ac.cn chenwf@cau.edu.cn.
authors.forename: Xiao Zeng
authors.initials: XZ
authors.lastname: Han
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China.
authors.forename: Zhao Jun
authors.initials: ZJ
authors.lastname: Ji
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City D.F., México.
authors.forename: En Tao
authors.initials: ET
authors.lastname: Wang
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.
authors.forename: Zhi Hong
authors.initials: ZH
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, China xzhan@neigaehrb.ac.cn chenwf@cau.edu.cn.
authors.forename: Wen Feng
authors.initials: WF
authors.lastname: Chen
mesh_terms: D000383:Agriculture / Q000379:methods*; D058448:Biota; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D055170:Plant Root Nodulation; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013025:Glycine max / Q000254:growth & development* / Q000382:microbiology
chemical_list: D004269:DNA, Bacterial