title: Partial 16S rRNA gene sequence diversity and numerical taxonomy of slow growing pigeonpea (Cajanus cajan L Millsp) nodulating rhizobia.
abstract: An investigation was carried out to determine the diversity of 30 isolates of slow growing pigeonpea nodulating rhizobia based on variations in partial sequences of the 16S rRNA gene and numerical analysis of 80 phenotypic traits. Phylogenetic analysis using molecular sequences of 23 isolates showed that ARPE1 separated from the other isolates at an average distance of >14% divergence level. The other isolates were all within 5% divergence from each other but separated into four main groups, with group 1 containing 16 of the 23 isolates. Comparisons to sequences of reference strains revealed that the group 1 isolates were phylogenetically closely related to the slow growing soybean nodulating rhizobia belonging to Bradyrhizobium elkanii, although only three of these isolates were able to nodulate soybean. Numerical analysis of phenotypic data of 19 isolates showed that 14 isolates clustered together in one branch of the phenogram, which included the group 1, group 2 and group 4 isolates from the phylogenetic analysis. The group 3 isolates were highly variable in the phenogram with similarity levels lower than 50% among these isolates.
authors.affiliation: Department of Life Sciences, The University of the West Indies, St Augustine, Trinidad and Tobago.
authors.forename: Adash
authors.initials: A
authors.lastname: Ramsubhag
authors.forename: Pathmanathan
authors.initials: P
authors.lastname: Umaharan
authors.forename: Alfred
authors.initials: A
authors.lastname: Donawa
mesh_terms: D020369:Bradyrhizobium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D007887:Fabaceae / Q000382:microbiology*; D014644:Genetic Variation; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation / Q000235:genetics; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000032:analysis* / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D012336:RNA, Ribosomal, 16S