Résumé
ln the context of climate change, increasing earth population, and burst of energy cost, legumes should contribute more to 60th food security and sustainable management of natural resources (water and soils) in the next years. A collaborative work with research groups in several developing countries during the past 20 years focused on investigation and sampling of local wild legumes (herbs, shrubs, and trees) with environmental/agronomic/forestry potential in West Africa and in the Mediterranean region. New symbiotic systems were discovered, resulting in new models for fundamental research, and new applications. This is, for one part, due to their associated microsymbionts, often belonging to unexpected bacterial groups with original physiological/metabolic properties, i.e. photosynthesis, free-living nitrogen fixation, methylothrophy, tolerance to extreme environmental conditions (salinity, aridity, heavy metals, a,d hydrocarbon breakdown), stem nodulation, and beneficial associations with non-Iegume plants (cereals). This may account for their wider adaptation to a variety of plant species and ecological habitats than previously thought, opening new insights for the domestication of these "multipurpose rhizobia". Indeed, new arable soils are required worldwide, often from degraded lands, affected by aridity, salinity, mining activities, and pollution. Rhizobia may thus participate as tools. Several examples picked up from our diversity investigations over recent years will be presented to illustrate either success stories of beneficial use of these new symbioses or reasonably good perspectives of application of research in different aspects, soil fertility regeneration/maintenance, food crop production optimization (i.e. green manure, nematode control, and associated cultures), and sustainable environmental management. We will present how federations farmers organizations at the local, regional, and national levels became active collaborative partners in these studies, and how results can be efficiently disseminated to !heir end-user members (smal1 fanners, NGOs, foresters, agronomists, cattle breeders, industrials, etc). (Texte intégral)