Photo credits: Vigna unguiculata nodules2 by Harry Rose - CC BY 2.0;

First analysis on cowpea-nodulating rhizobia in European soils

Until now, there was a very limited information about cowpea rhizobia in European soils. In the present study, developed in Greece, investigators analyzed, for the first time, the genetic and phenotypic diversity of indigenous cowpea-nodulating rhizobia.

Despite that much research has been done on cowpea-nodulating bacteria, in various countries around the world, the same wasn’t happening in European soils.

The cowpea (Vigna unguiculata) forms nitrogen-fixing root nodules with diverse symbiotic bacteria, mainly slow-growing rhizobial species belonging to the genus Bradyrhizobium, although few studies have reported the isolation of fast-growing rhizobia under laboratory and field conditions.

With that study, there are already new findings related with putative novel lineages of Bradyrhizobium, that can possiblyrepresent novel species and/or symbiovarsthat have been isolated and phylogenetically classified.

Additionally, novel lineages of Ensifer were isolated, which establish a new symbiovar for which the name sv. aegeanense was proposed. These findings further confirm the promiscuity of cowpea and extend the knowledge regarding the diversity, distribution and evolution of cowpea-nodulating rhizobia in European soils.

When selecting novel strains, adapted to the local environmental conditions, is important to consider previous investigations, namely the studies with indigenous rhizobia in fields without rhizobial inoculation history.

Such strains often exhibit a better performance in similar habitats, therefore they are more preferable for inoculant formulations.