Genetic Diversity of Acacia seyal Del. Rhizobial Populations Indigenous to Senegalese Soils in Relation to Salinity and pH of the Sampling Sites

• Published in: Microbial ecology Vol. 54; no. 3; pp. 553 - 566
• Main Authors: Diouf, Diegane, Samba-Mbaye, Ramatoulaye, Lesueur, Didier, Ba, Amadou T, Dreyfus, Bernard, de Lajudie, Philippe, Neyra, Marc
• Format: Journal Article
• Language: English
• Published: New York, NY New York : Springer-Verlag 01-10-2007; Springer Science + Business Media, Inc; Springer; Springer Nature B.V
• Subjects: Acacia; Acacia - microbiology; Adaptability; Agrobacterium; Agroforestry; Alkaline soils; Bacteria; Biological and medical sciences; Burkholderia; Environmental stress; Forest soils; Fundamental and applied biological sciences. Psychology; Genetic diversity; Genetic Variation; Genotypes; Hydrogen-Ion Concentration; Mesorhizobium; Microbiology; Molecular Sequence Data; Nitrogen fixation; Nodulation; Nodules; Phylogeny; Plants; Polymorphism, Restriction Fragment Length; Rhizobiaceae - classification; Rhizobiaceae - genetics; Rhizobiaceae - growth & development; Ribosomal DNA; RNA, Ribosomal, 16S - genetics; RNA, Ribosomal, 23S - genetics; Saline soils; Salinity; Senegal; Sequence Analysis, DNA; Sinorhizobium; Soil environment; Soil Microbiology; Soil salinity; Soil samples; Symbiosis; Senegal; West Africa; Africa; Origin; Tropical zone; Ribosomal DNA; Samplings; Environmental factor; Climatic zone; Nodule; Profile; Saline soil; Aromatic extract; Agrobacterium; Dicotyledones; Angiospermae; 16S-RNA; pH; Bacteria; Hardwood forest tree; Gram negative bacteria; Acacia seyal; Interspecific association; Genotype; Genetic diversity; Rhizobium; Salinity; Polymerase chain reaction; Restriction fragment length polymorphism; Leguminosae; Spermatophyta; Rhizobiaceae; Interspecific relation
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-007-9243-0

The occurrence and the distribution of rhizobial populations naturally associated to Acacia seyal Del. were characterized in 42 soils from Senegal. The diversity of rhizobial genotypes, as characterized by polymerase chain reaction restriction fragment length polymorphism (RFLP) analysis of 16S-23S rDNA, performed on DNA extracted from 138 nodules resulted in 15 clusters. Results indicated the widespread occurrence of compatible rhizobia associated to A. seyal in various ecogeographic areas. However, the clustering of rhizobial populations based on intergenic spacer (IGS) RFLP profiles did not reflect their geographic origin. Four genera were discriminated on the basis of 16S rRNA gene sequences of the strains representative for the IGS-RFLP profiles. The majority of rhizobia associated to A. seyal were affiliated to Mesorhizobium and Sinorhizobium 64 and 29%, respectively, of the different IGS-RFLP profiles. Our results demonstrate the coexistence inside the nodule of plant-pathogenic non-N₂-fixing Agrobacterium and Burkholderia strains, which induced the formation of ineffective nodules, with symbiotic rhizobia. Nodulation was recorded in saline soils and/or at low pH values or in alkaline soils, suggesting adaptability of natural rhizobial populations to major ecological environmental stress and their ability to establish symbiotic associations within these soil environments. These results contribute to the progressing research efforts to uncover the biodiversity of rhizobia and to improve nitrogen fixation in agroforestry systems in sub-Saharan Africa.