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Since their domestication, root crops have been clonally distributed over wide geographical distances. The bottle necks induced by the introduction process often resulted in varieties with narrow genetic bases, now increasing smallholders' vulnerability to forthcoming agro-climatic changes. The question is: how can we develop adapted varieties, considering climatic uncertainties, the constraints in developing countries and the characteristics of the root crop species involved? These species share common biological traits: they are asexually propagated in farmers' fields, flowering ability of varieties is erratic, they have variable ploidy levels but are predominantly allogamous and highly heterozygous. Breeding is a slow process conducted on research stations even though it is widely accepted that G x E interactions are highly significant. The distribution of selected clones is then constrained by their low multiplication rate, the large number of smallholders, their geographical isolation, the absence of a 'seed' industry and strict international regulations. This paper presents a review of studies on root crops genetic diversity, their germplasm management systems and breeding constraints. It attempts to propose a new approach to strengthen smallholders' capacity to adapt to forthcoming changes. Suggestions are made for future research to address adaptation, taking into consideration improvement program needs at the national level. The geographical distribution of allelic diversity appears as a practical and cost-efficient approach. (Résumé d'auteur)