Ecological adaptation and phylogenetic analysis of microsymbionts nodulating Polhillia, Wiborgia and Wiborgiella species in the Cape fynbos, South Africa

Résumé

Abstract Polhillia,WiborgiaandWiborgiellaspecies are shrub legumes endemic to the Cape fynbos of South Africa. They have the ability to fix atmospheric N2when in symbiosis with soil bacteria called ‘rhizobia’. The aim of this study was to assess the morpho-physiological and phylogenetic characteristics of rhizobia associated with the nodulation ofPolhillia,WiborgiaandWiborgiellaspecies growing in the Cape fynbos. The bacterial isolates from root nodules consisted of a mixture of fast and intermediate growers that differed in colony shape and size. The isolates exhibited tolerance to salinity (0.5–3% NaCl) and pH (pH 5–10) and different antibiotic concentrations, and could produce 0.51 to 51.23 µg mL−1of indole-3-acetic acid (IAA), as well as solubilize tri-calcium phosphate. The ERIC-PCR results showed high genomic diversity in the rhizobial population and grouped them into two major clusters. Phylogenetic analysis based on 16S rRNA,atpD,glnII,gyrB,nifHandnodCgene sequences revealed distinct and novel evolutionary lineages related to the genusRhizobiumandMesorhizobium, with some of them being very close toMesorhizobium australicum. However, the phylogenetic analysis ofglnIIandnifHgenes of some isolates showed incongruency.

Citer ce document

Accès au document

Ce document est hébergé sur son dépôt institutionnel d'origine.

Auteur(s)

Statistiques

Consultations : 1

Téléchargements : 0