Symbiose Rhizobium-Lupin. Biodiversité des microsymbiotes et leur caractérisation à partir des nodules racinaires de la Légumineuse Lupinus angustifolius.

Abstract

In this study a total of 80 bacterial strains isolated from root nodules of Lupinus angustifolius grown wild in the North-Eastern Algerian region of El Tarf, The nodulation test confirmed the ability of 64 isolates to nodulate their original host plant. RAPD –PCR, distribut these isolates into 17 differents profiles. Analysis of 16S rRNA gene sequences of a representative strain of each profil showed that all the isolates belonged to the genus Bradyrhizobium, but their affiliation at the species level was not clear. For this reason the phylogenetic study based on the sequencing of housekeeping genes (glnII, recA) as well as symbiotic genes (nodC) was conducted. This analysis confirmed and clarified the previous results. Indeed, revealed the distribution of the strains into four large groups phylogenetically different. All the examined strains form a homogeneous group within the genistearum symbiovar of Bradyrhizobium. The strains were the subject of a phenotypic characterization namely: cultural characters, cellular, nutritional, physiological and biochemical, which confirm the biodiversity of Lupinus angustifolius strains isolated from Algeria. Based on the results obtained, this study revealed the diversity of the rhizobia nodulating Lupinus angustifolius, with some potentially new Bradyrhizobium species, requiring further taxonomic characterization for confirmation and formal description.