Genetic diversity of Acacia tortilis ssp. raddiana rhizobia in Tunisia assessed by 16S and 16S-23S rDNA genes analysis

• Published in: Journal of applied microbiology Vol. 100; no. 3; pp. 436 - 445
• Main Authors: Ben Romdhane, S, Nasr, H, Samba-Mbaye, R, Neyra, M, Ghorbal, M.H, Lajudie, P. De
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2006; Blackwell Science; Oxford University Press
• Subjects: 16S rRNA; 16S‐23S rRNA spacer; Acacia - genetics; Acacia - microbiology; Acacia tortilis; Bacteria; Biological and medical sciences; diversity; DNA, Bacterial - genetics; DNA, Ribosomal - genetics; DNA, Ribosomal Spacer - genetics; Ensifer; Fundamental and applied biological sciences. Psychology; genes; genetic variation; Genetic Variation - genetics; host plants; intergenic DNA; Microbiology; nodulation; pathogenicity; Phylogeny; Plant Diseases - genetics; Plant Roots - microbiology; polymerase chain reaction; Polymerase Chain Reaction - methods; Polymorphism, Restriction Fragment Length; restriction fragment length polymorphism; rhizobia; Rhizobium; Rhizobium - genetics; Rhizobium - isolation & purification; ribosomal DNA; ribosomal RNA; RNA, Bacterial - genetics; RNA, Ribosomal, 16S - genetics; RNA, Ribosomal, 23S - genetics; Sequence Analysis, RNA - methods; soil; Symbiosis; symbiotic efficiency; Tunisia; Tunisia; Africa; Symbiosis; 16S rRNA; Genetic variability; Applied microbiology; Ribosomal DNA; Genetic diversity; Rhizobium; diversity; Leguminosae; Acacia tortilis; Gene; rhizobia; symbiotic efficiency; Efficiency; Ribosomal RNA; Dicotyledones; Angiospermae; 16S-RNA; Bacteria; Spermatophyta; Rhizobiaceae; 16S-23S rRNA spacer
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2005.02765.x

In order to understand the genetic diversity of Acacia tortilis ssp. raddiana-rhizobia in Tunisia, isolates from nine geographical locations were obtained and analysed. Characterization using restriction fragment length polymorphism analysis (RFLP) of PCR-amplified 16S rRNA gene and the intergenic spacer (IGS) between the 16S and 23S rRNA genes was undertaken. Symbiotic efficiency of the strains was also estimated. Analysis of the 16S rRNA by PCR-RFLP showed that the isolates were phylogenetically related to Ensifer ssp., Rhizobium tropicii-IIA, and Rhizobium tumefaciens species. Analysis of 16S-23S spacer by PCR-RFLP showed a high diversity of these rhizobia and revealed eleven additional groups, which indicates that these strains are genetically very diverse. Full 16S rRNA gene-sequencing showed that the majority of strains form a new subdivion inside the genera Ensifer, with Ensifer meliloti being its nearest neighbour. Nodulation test performed on the plant host demonstrated differences in the infectivity among the strains. Rhizobial populations that nodulate specifically and efficiently Acacia tortilis ssp. raddiana in representative soils of Tunisia is dominated by E. meliloti-like genomospecies. This paper provides the first clear characterization and symbiotic efficiency data of rhizobia strains nodulating A. tortilis in Tunisia.