Genetic diversity  and phylogeny of rhizobia isolated from Caragana microphylla growing in  desert soil in Ningxia, China.
Rhizobia  are soil bacteria with the capacity to induce nitrogen-fixing nodules on the  roots or stems of legume plants. A total of 40 bacterial isolates from the root  nodules of Caragana microphylla growing in desert soil in Ningxia,  China, were analyzed for genetic diversity and phylogenetic position. These  isolates were classified into 7 types of 16S ribosomal DNA (rDNA) using  polymerase chain reaction-restriction fragment length polymorphism analysis.  They were grouped into 4 clades, Rhizobium-Agrobacterium, Sinorhizobium, Phyllobacterium, and Bradyrhizobium, when the phylogenies of 16S  rDNA, recA, and atpD genes were applied. Phylogenetic analysis  showed that the tree generated from the 16S rDNA sequencing agreed with that  produced from the recA and atpD genes. By analyzing phylogenetic  relationship using the 3 loci, the isolates in the branches of Phyllobacterium and Sinorhizobium could be identified as P. brassicacearum and S. meliloti. The isolates in the branch of Rhizobium-Agrobacterium were the most abundant microsymbiont of C. microphylla and were  designated R. leguminosarum, R. galegae, R. alamii,  and A. tumefaciens. Two isolates with low sequence similarity to the  known species of Bradyrhizobium might be novel species in this genus.
Key Laboratory of the Ministry of Education for the Conservation and Utilization of Special Biological Resources of Western China, Ningxia, China.
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J
Dai
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X
Liu
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Wang
D001483:Base Sequence; D032602:Caragana / Q000254:growth & development* / Q000382:microbiology*; D002681:China; D003889:Desert Climate; D005798:Genes, Bacterial / Q000235:genetics; D014644:Genetic Variation; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012231:Rhizobium / Q000235:genetics* / Q000302:isolation & purification*; D017422:Sequence Analysis, DNA
D012336:RNA, Ribosomal, 16S