Genetic diversity of root nodulating bacteria associated with Retama sphaerocarpa in sites with different soil and environmental conditions.
The genetic diversity of root nodulating bacteria isolated from Retama sphaerocarpa was studied using BOX-A1R PCR and phylogenetic analysis of the 16S rRNA region, as well as the housekeeping genes atpD, glnII and recA. A total of 193 isolates were obtained from eight different sites with different soil and environmental conditions in the Iberian Peninsula. These isolates corresponded to 31 different strains that successfully nodulated R. sphaerocarpa seedlings in reinoculation trials. About one-third of the strains clustered with B. canariense or B. cytisi within Bradyrhizobium group I. The remaining strains clustered with B. elkanii/B. pachyrhizi within Bradyrhizobium group II or in separate clades that could represent new lineages. Based on the 16S rRNA and combined atpD+glnII+recA sequences, two to three lineages of root nodulating bacteria were found at each sampling site, except for Collado Garcia where five species were detected. B. canariense and B. elkanii/B. pachyrhizi were the most abundant species, whereas the least abundant were those related to B. retamae and a putative new lineage. B. canariense was found only in soils with neutral and acid pH, whereas B. retamae was the dominant species in alkaline soils.
Centro de Ecologia Funcional, Departamento de Ciências da Vida, Universidade de Coimbra, Coimbra, Portugal. Electronic address: susanare@ci.uc.pt.
Susana
S
Rodríguez-Echeverría
Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, Agencia Estatal Consejo Superior de Investigaciones Científicas, Granada, Spain.
Silvia
S
Moreno
Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, Agencia Estatal Consejo Superior de Investigaciones Científicas, Granada, Spain.
Eulogio J
EJ
Bedmar
D020369:Bradyrhizobium / Q000145:classification* / Q000235:genetics*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology*; D014644:Genetic Variation; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D010802:Phylogeny; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D011174:Portugal; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013030:Spain
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012987:Soil
Bradyrhizobium; Iberian Peninsula; Phylogeny; Retama; Soil pH; Symbiosis