Original Paper

Theoretical and Applied Genetics

, Volume 114, Issue 2, pp 237-248

First online:

Local genetic diversity of sorghum in a village in northern Cameroon: structure and dynamics of landraces

  • Adeline BarnaudAffiliated withCIRAD, UPR 67 Gestion des Ressources Génétiques et Dynamiques Sociales, UMR 5175-CEFE (Centre d’Ecologie Fonctionnelle et Evolutive) Email author 
  • , Monique DeuAffiliated withCIRAD, UMR 1096-PIA, TA 40/03
  • , Eric GarineAffiliated withLaboratoire d’Ethnologie et de Sociologie Comparative, CNRS, Université Paris X-Nanterre, MAE,
  • , Doyle McKeyAffiliated withCIRAD, UPR 67 Gestion des Ressources Génétiques et Dynamiques Sociales, UMR 5175-CEFE (Centre d’Ecologie Fonctionnelle et Evolutive)
  • , Hélène I. JolyAffiliated withCIRAD, UPR 67 Gestion des Ressources Génétiques et Dynamiques Sociales, UMR 5175-CEFE (Centre d’Ecologie Fonctionnelle et Evolutive)

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Abstract

We present the first study of patterns of genetic diversity of sorghum landraces at the local scale. Understanding landrace diversity aids in deciphering evolutionary forces under domestication, and has applications in the conservation of genetic resources and their use in breeding programs. Duupa farmers in a village in Northern Cameroon distinguished 59 named sorghum taxa, representing 46 landraces. In each field, seeds are sown as a mixture of landraces (mean of 12 landraces per field), giving the potential for extensive gene flow. What level of genetic diversity underlies the great morphological diversity observed among landraces? Given the potential for gene flow, how well defined genetically is each landrace? To answer these questions, we recorded spatial patterns of planting and farmers’ perceptions of landraces, and characterized 21 landraces using SSR markers. Analysis using distance and clustering methods grouped the 21 landraces studied into four clusters. These clusters correspond to functionally and ecologically distinct groups of landraces. Within-landrace genetic variation accounted for 30% of total variation. The average F is over landraces was 0.68, suggesting high inbreeding within landraces. Differentiation among landraces was substantial and significant (F st = 0.36). Historical factors, variation in breeding systems, and farmers’ practices all affected patterns of genetic variation. Farmers’ practices are key to the maintenance, despite gene flow, of landraces with different combinations of agronomically and ecologically pertinent traits. They must be taken into account in strategies of conservation and use of genetic resources.