Résumé
Coffee Coffea canephora Pierre genetic improvement: Acquired knowledge, strategies and perspectives
Coffea canephora coffee varietal improvement stands as a huge challenge towards better productivity and hence better income for producers. Opportunities are numerous : the genetic diversity of the species is well documented, genetic parameters are well established for the main characteristics of interest and genomic resources are accumulating. However, constraints are also present: in particular, the specific history of C. canephora growing and breeding has led to an unequal access to the whole genetic diversity among breeders around the world. For instance, only Cote d'Ivoire could implement a Reciprocal Recurrent Selection (RRS) programme, representing a major innovation for the comprehensive use of genetic resources, as only this country has the whole genetic diversity available in its field collections. This RRS strategy is adapted to hybrid seed varietal release, more suitable than clonal cuttings for a massive varietal diffusion. Apart from Cote d'Ivoire, countries are often relying on clonal mass selection from recombining populations whose genetic background is not always clearly described. C. canephora genomic resources are now sufficient to support breeding programmes. The coffee genome is about to be sequenced. Strategic choices for optimal use of these resources towards better genetic gains deserve deep reflexion based on the acquired experience with other crops: key elements for these choices are discussed.