title: Genetic diversity, community structure and distribution of rhizobia in the root nodules of Caragana spp. from arid and semi-arid alkaline deserts, in the north of China.
abstract: The genetic diversity of 88 Caragana nodule rhizobial isolates, collected from arid and semi-arid alkaline sandy soils in the north of China, was assessed by PCR-RFLP of the 16S rRNA gene and the 16S-23S IGS, as well as the phylogenies of housekeeping genes (atpD, glnII and recA) and symbiotic genes (nodC and nifH). Of the 88 strains, 69 were placed in the genus Mesorhizobium, 16 in Rhizobium and 3 in Bradyrhizobium. Mesorhizobium amorphae, Mesorhizobium septentrionale, Mesorhizobium temperatum and Rhizobium yanglingense were the four predominant microsymbionts associated with Caragana spp. in the surveyed regions, and M. septentrionale was widely distributed among the sampling sites. Phylogenies of nodC and nifH genes showed that two kinds of symbiotic genes existed, corresponding to Mesorhizobium and Rhizobium, respectively. Available phosphorous (P) and potassium (K) contents were the main soil factors correlated with the distribution of these rhizobia in the sampling regions. Positive correlations between the available higher P content/lower K content and the dominance of Mesorhizobium species (M. temperatum, M. amorphae and M. septentrionale), and between the lower P content/higher K content and the dominance of R. yanglingense were found.
authors.affiliation: State Key Laboratory of Agrobiotechnology and College of Biological Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Mao
authors.initials: M
authors.lastname: Li
authors.forename: Yán
authors.initials: Y
authors.lastname: Li
authors.forename: Wen Feng
authors.initials: WF
authors.lastname: Chen
authors.forename: Xin Hua
authors.initials: XH
authors.lastname: Sui
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Yàn
authors.initials: Y
authors.lastname: Li
authors.forename: En Tao
authors.initials: ET
authors.lastname: Wang
authors.forename: Wen Xin
authors.initials: WX
authors.lastname: Chen
mesh_terms: D020561:Alphaproteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics; D058448:Biota; D032602:Caragana / Q000382:microbiology*; D002681:China; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D003889:Desert Climate; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010758:Phosphorus / Q000032:analysis; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology; D012150:Polymorphism, Restriction Fragment Length; D011188:Potassium / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D058441:Rhizosphere; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D012987:Soil; D010758:Phosphorus; D011188:Potassium