title: Genetic diversity and community structure of rhizobia nodulating Sesbania cannabina in saline-alkaline soils.
abstract: Sesbania cannabina is a plant that grows naturally along the seashores in Rudong County, China (RDC) and it has been introduced into the Yellow River Delta (YRD) as a pioneer plant to improve the saline-alkaline soils. In order to investigate the diversity of S. cannabina rhizobia in these soils, a total of 198 rhizobial isolates were characterized and phylogenetic trees were constructed based on data from multilocus sequence analysis (MLSA) of the housekeeping genes recA, atpD and glnII, as well as 16S rRNA. Symbiotic features were also studied by establishing the phylogeny of the symbiotic genes nodA and nifH, and by performing nodulation assays. The isolates had highly conserved symbiotic genes and were classified into nine genospecies belonging to the genera Ensifer, Agrobacterium, Neorhizobium and Rhizobium. A unique community structure was detected in the rhizobia associated with S. cannabina in the saline-alkaline soils that was characterized by five novel genospecies and four defined species. In addition, Ensifer sp. I was the predominant rhizobia in YRD, whereas Ensifer meliloti and Neorhizobium huautlense were the dominant species in RDC. Therefore, the study demonstrated for the first time that this plant strongly selected the symbiotic gene background but not the genomic background of its microsymbionts. In addition, biogeographic patterns existed in the rhizobial populations associated with S. cannabina, which were mainly correlated with pH and salinity, as well as the mineral nutrient contents. This study provided novel information concerning the interaction between soil conditions, host plant and rhizobia, in addition to revealing the diversity of S. cannabina rhizobia in saline-alkaline soils.
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China.
authors.forename: Xiangyue
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China.
authors.forename: Yajing
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, 11340 Mexico City, D.F., Mexico.
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, 264003 Yantai, China.
authors.forename: Chenggang
authors.initials: C
authors.lastname: Ren
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Dongying Institute of Agriculture Sciences, 257000 Dongying, China.
authors.forename: Hualing
authors.initials: H
authors.lastname: Xu
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Wu
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China.
authors.forename: Yunzhao
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, China. Electronic address: zhxie@yic.ac.cn.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Xie
mesh_terms: D000217:Acyltransferases / Q000235:genetics; D060054:Agrobacterium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics; D058885:Multilocus Sequence Typing; D010088:Oxidoreductases / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics; D012231:Rhizobium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D053204:Root Nodules, Plant / Q000382:microbiology*; D049931:Sesbania / Q000382:microbiology*; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013559:Symbiosis / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012987:Soil; D014157:Transcription Factors; D010088:Oxidoreductases; C029130:nitrogenase reductase; D000217:Acyltransferases; C060770:NodA protein, Rhizobiales; D011938:Rec A Recombinases
keywords: Biogeography; Interactions; Phylogeny; Saline–alkaline soil; Sesbania-rhizobia