Synthèse Caractérisation de l'agrobiodiversité de l'agrosystème aux gènes Analyse multiéchelle de la diversité génétique des sorghos : compréhension des processus évolutifs pour la conservation in situ

Multi-scale analysis of sorghum genetic diversity: Understanding the evolutionary processes for in situ conservation Using microsatellite genetic markers, we analyzed 1,518 sorghum samples collected at different spatial scales in Burkina Faso, Mali, Niger, and in the village of Wante, from the landrace to the country scale. Genetic diversity and differentiation parameters were estimated to assess the effects of the main evolutionary processes on sorghum genetic diversity. The genetic variability found within a variety is mainly the result of the sorghum reproduction biology and the genetic drift process caused by the limited number of reproductive individuals at the time of variety introduction into a household or each year when farmers select their seeds. At the village scale, a low correlation is observed between the diversity of vernacular names and the genetic diversity assessed by microsatellites. No spatial genetic structuration is observed among villages more than 30 kilometers apart. This point highlightss that traditional seed systems operate at a very local scale. In Mali, a Tires a part : F. Sagnard Cahiers Agricultures vol. 17, n° 2, mars-avril 2008 114 doi:10.1/agr.2008.0180