Root-Nodule Bacteria of Legumes Growing in Semi-Arid African Soils and Other Areas of the World

In Africa, arid and semi-arid soils are characterized by a diverse occurrence of plants including nodulated legumes which are adapted to the prevailing and often harsh environmental conditions. Such soils also harbour a large diversity of indigenous rhizobial symbionts (comparable to legume diversity) and other bacterial endophytes that have a potential to be developed into elite strains to be used as inoculum. However, very few studies have investigated the diversity of root-nodule bacteria on African soils, the main reason being that funds for research are often lacking. Discoveries of new rhizobial species are to be expected from different soil ecologies that are likely to be inhabited by various types of microorganisms. It is concluded that the semi-arid and arid African soils have rhizobia that is possibly as equally diverse as their host legumes. Research in these areas is likely to find novel species with a great potential for use in agricultural systems.