Distribution and Diversity of Rhizobial Populations Associated with <i>Acacia senegal</i> (L.) Willd. Provenances in Senegalese Arid and Semiarid Regions

Abstract

Distribution and diversity of rhizobial strains associated with Acacia senegal (L.) Willd. in relation to seed provenances in soils from arid (Dahra) and semiarid (Goudiry) zones of Senegal were investigated. PCR-RFLP performed on 16S-23S rDNA intergenic spacer (IGS) of nodule crude extracts revealed a high genetic diversity of rhizobial strains, which was higher in the semiarid region than in the arid region. The distribution of rhizobial populations was influenced by soil physical and chemical characteristics, and by A. senegal provenances as shown by the analysis of correspondence. In contrast, the phenotypic diversity of rhizobial strains was not correlated with the soil origin. The phylogenetic tree (performed by the maximum likelihood algorithm) of IGS 16S-23S sequences showed that most of the rhizobial strains nodulating A. senegal were closely related to Mesorhizobium plurifarium. Our results showed that rhizobial taxa associated with A. senegal were mainly distributed according to soil physical and chemical characteristics, and A. senegal provenances. A large subset of A. senegal root-nodulating bacteria had high diversity that correlated with the most favourable environmental conditions. Understanding the diversity and distribution of rhizobial strains may be exploited in the formulation of A. senegal inoculants for different seed provenances for resilience to soil stresses in various environmental conditions.

Phenotypic characterisation of rhizobia nodulating differentmorphotypes of Vachellia karroo

“…About 37.5% of the strains grew in all the heavy metals at the concentrations used in this study, a characteristics of other Vachellia rhizobia (Bakhoum et al 2014) (Table 3). The soil from which the rhizobia isolates were extracted did not influence the clustering of the isolates in relation to their ability to tolerate heavy metals.…”

Senegalia senegal (synonym: Acacia senegal), its importance to sub-Saharan Africa, and its relationship with a wide range of symbiotic soil microorganisms

“…The data suggested that the rhizobia that associate with S. senegal are characterized by the soil from which they were collected, and studies performed in Senegal support these conclusions. Further support comes from investigations where the diversity of nodulating bacteria associated with S. senegal was found to be high when the soil physical and chemical parameters were favorable (Bakhoum et al, 2014). These authors also reported that nodulating bacteria for S. senegal appeared to be selected by seed provenance.…”

“…Studies performed in Senegal have shown that even though S. senegal is nodulated by the genus Rhizobium, its main symbionts are strains phylogeneticaly related to Mesorhizobium plurifarium (Bakhoum et al, 2014;Fall et al, 2008;Sarr et al, 2005b,a). However, some of the strains that nodulate S. senegal and previously described as M. plurifarium belong to a new species .…”

“…Senegalia senegal is symbiotic with soil microorganisms, especially rhizobia and Arbuscular Mycorrhizal Fungi (AMF). Rhizobia contribute to the global nitrogen cycle (Sprent, 1994), and a number of different rhizobial taxa and strains establish nitrogen-fixing nodules on S. senegal roots (Bakhoum et al, 2014;de Lajudie et al, 1998;Fall et al, 2008;Nick et al, 1999;Njiti and Galiana, 1996;Odee et al, 1995Odee et al, , 1997. AMF are widespread and are critical to establishing a healthy soil microbiome.…”

Dénombrement Des Populations Naturelles De Rhizobium Du Pois Chiche (Cicer Arietinum) Dans Différents Sols Du Maroc

“…De ce fait, il serait souhaitable que d'autres systèmes de culture des plantes soient essayés. Sachant que la distribution des populations rhizobiennes est corrélée aux caractéristiques physicochimiques des sols (Bakhoum et al, 2017), il est souhaitable de trouver une nouvelle méthode qui consiste à enrichir les dilutions de sols avant de les inoculer.…”