title: Phenotypic and genotypic diversity of rhizobia nodulating Pterocarpus erinaceus and P. lucens in Senegal.
abstract: A total of fifty root nodules isolates of fast-growing and slow growing rhizobia from Pterocarpus ennaceus and Pterocarpus lucens respectively native of sudanean and sahelian regions of Senegal were characterized. These isolates were compared to representative strains of known rhizobial species. Twenty-two new isolates were slow growers and twenty-eight were fast growers. A polyphasic approach was performed including comparative total protein sodium dodecyl sulphate polyacrylamide gel (SDS-PAGE) profile analysis; 16S rDNA and 16S-23S rDNA intergenic spacer (IGS) sequence analysis. By SDS-PAGE the slow growing isolates grouped in one major cluster containing reference strains of Bradyrhizobium sp. including strains isolated in Africa, in Brazil and in New Zealand. Most of the fast-growing rhizobia grouped in four different clusters or were separate strains related to Rhizobium and Mesorhizobium strains. The 16S rDNA and 16S-23S rDNA IGS sequences analysis showed accurately the differentiation of fast growing rhizobia among the Rhizobium and Mesorbizobium genospecies. The representative strains of slow growing rhizobia were identified as closely related to Bradyrbizobium elkanii and Bradyrhizobium japonicum. Based on 16S rDNA sequence analysis, one slow growing strain (ORS199) was phylogenetically related to Bradyrbizobium sp. (Lupinus) and Blastobacter denitrificans. This position of ORS 199 was not confirmed by IGS sequence divergence. We found no clear relation between the diversity of strains, the host plants and the ecogeographical origins.
authors.affiliation: Université Cheikh Anta Diop, FST, Departement de B.V., Dakar, Sénégal. Samba.sylla@dakar.ird.sn
authors.forename: Samba Ndao
authors.initials: SN
authors.lastname: Sylla
authors.forename: Ramatoulaye Thiaba
authors.initials: RT
authors.lastname: Samba
authors.forename: Marc
authors.initials: M
authors.lastname: Neyra
authors.forename: Ibrahima
authors.initials: I
authors.lastname: Ndoye
authors.forename: Eric
authors.initials: E
authors.lastname: Giraud
authors.forename: Anne
authors.initials: A
authors.lastname: Willems
authors.forename: Philippe
authors.initials: P
authors.lastname: de Lajudie
authors.forename: Bernard
authors.initials: B
authors.lastname: Dreyfus
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis; D020369:Bradyrhizobium / Q000145:classification* / Q000166:cytology / Q000235:genetics; D021901:DNA, Intergenic; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D014644:Genetic Variation; D005838:Genotype; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D035721:Pterocarpus / Q000382:microbiology*; D012329:RNA, Bacterial / Q000032:analysis; D012335:RNA, Ribosomal / Q000032:analysis*; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012338:RNA, Ribosomal, 23S / Q000032:analysis; D012231:Rhizobium / Q000145:classification* / Q000166:cytology / Q000235:genetics; D012675:Senegal; D016415:Sequence Alignment; D012988:Soil Microbiology
chemical_list: D001426:Bacterial Proteins; D021901:DNA, Intergenic; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S