Gueye Fatou auteur aut IRD Moulin Lionel auteur aut IRD Sylla S. auteur aut IRD Ndoye I. auteur aut IRD Béna Gilles auteur aut IRD text journalArticle eng text/pdf born digital access Herb legumes have great potential for rehabilitation of semi-arid degraded soils in Sahelian ecosystems as they establish mutualistic symbiosis with N-2-fixing rhizobia. A phylogenetic analysis was performed for 78 root nodule bacteria associated with the common Sahelian herb legume Zornia glochidiata Reichb ex DC in Senegal. Based on ITS (rDNA16S-23S) and recA sequences, these strains were shown to belong to the two genera Bradyrhizobium? and Azorhizobium. Strains of this latter, although frequent, formed small and ineffective nodules and suggested a parasitism rather than a symbiotic association. A potential negative effect of Azorhizobium on Zornia growth was tested for when inoculated alone or in association with a Bradyrhizobium strain. Bradyrhizobium isolates were distributed in four groups. Groups A and B were two sister clades in a larger monophyletic group also including Bradyrhizobium liaoningense, Bradyrhizobium yuanmingense, and Bradyrhizobium japonicum. Strains of cluster D fell in a sister clade of the photosynthetic Bradyrhizobium sp. group, including ORS278, whereas group C appeared to be divergent from all known Bradyrhizobium Clusters. Amplified fragment length polymorphism (AFLP) clustering was congruent with ITS and recA phylogenies, but displayed much more variability. However, within the main Bradyrhizobium clades, no obvious relationship could be detected between clustering and geographical origin of the strains. Each sub-cluster included strains sampled from different locations. Conversely, Azorhizobium strains showed a tendency in the phylogeny to group together according to the site of sampling. The predominance of ineffective Azorhizobium strains in the nodules of Zornia roots, the large Bradyrhizobium genetic diversity and the geographical genetic diversity pattern are explored. specialized Bradyrhizobium Azorhizobium Zornia glochidiata Symbioses Nitrogen fixation Parasitism AFLP Phylogeny 084 32 6 387-399 2009 0723-2020 https://www.documentation.ird.fr/hor/fdi:010057521 10.1016/j.syapm.2009.04.004 0723-2020 [F B010057521] https://www.documentation.ird.fr/hor/fdi:010057521 https://www.documentation.ird.fr/intranet/publi/depot/2012-10-26/010057521.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2009-10-07 2017-08-23 fdi:010057521 fre