title: [Numerical taxonomy and 16S rDNA PCR-rFLP analysis of rhizobial strains isolated from root nodules of cowpea and mung bean grown in different regions of China].
abstract: Seventy-nine rhizobial strains, isolated from root nodules of cowpea ( Vigna unguiculata ) and mung bean (Vigna radiata ) grown in different regions of China, were studied by a fuzzy cluster analysis of 128 phenotypic characteristics. The phenotypic characterization of these strains showed that most of these strains had high stress resistance. For instance, most of them could grow from pH 5.0 to pH 11.0. Over 85% of these strains could grow well on YMA plate at 37 degrees C and several of them even could grow after a 45 minutes hot shock at 60 degrees C. Some strains had a tolerance to high concentration of Bacitracin (400 microg/mL) . The result of the fuzzy cluster analysis showed that all the strains were clustered into 2 groups, slow growers and fast growers, at the similarity level of 63.5% . At the similarity level of 79 %, there were 7 subgroups further separated. Based upon the result of the numerical taxonomy, these strains together with 22 reference stains were analyzed by the 16S rDNA PCR-RFLP. Thirty-four genotype profiles were obtained from the fingerprinting of the 16S rDNA PCR-RFLP. These strains were analyzed by GelCompare II software and clustered into 7 groups at the similarity level of 91% , which were consonant with the 7 subgroups clustered at the similarity level of 79% in numerical taxonomy. The results of numerical taxonomy and 16S rDNA PCR-RFLP analysis showed that all of the seventy-nine rhizobial Bradyrhizobium, strains isolated from root nodules of cowpea and mung bean were clustered into four genera: Agrobacterium, Rhizobium and Sinorhizobium, respectively. An individual clade without any reference stains, which was composed of CCBAU 45071, CCBAU 45111-1 and CCBAU 45248, might be a new species of Rhizobium. Overall, the study results demonstrated a high phenotypic and phylogenetic diversity of rhizobial strains nodulating cowpea and mung bean grown in different geographic regions of China.
authors.affiliation: Key Laboratory of Agro-Microbial Resource and Application, Ministry of Agriculture, College of Biological Sciences, China Agriculture University, Beijing 100094, China.
authors.forename: Yong-fa
authors.initials: YF
authors.lastname: Zhang
authors.forename: Feng-qin
authors.initials: FQ
authors.lastname: Wang
authors.forename: Wen-xin
authors.initials: WX
authors.lastname: Chen
mesh_terms: D020369:Bradyrhizobium / Q000145:classification* / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology*; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D012231:Rhizobium / Q000145:classification* / Q000235:genetics; D020579:Sinorhizobium / Q000145:classification* / Q000235:genetics; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S