Application of molecular markers to describing the genetic structure of cassava gene pools

The genetic resources available for cassava improvement include advanced breeding lines, collected landraces and the cropss wild relatives. Information about the structure of these gene pools is important in the development of sound germplasm conservation and use strategies. RAPD markers have been applied to describing relationships among elite clones from the CIAT cassava breeding program. The experimental material represents adapted germplasm selected in five distinct edaphoclimatic zones important to cassava production. Results of correspondence analysis and genetic distance estimates based on data from 196 polymorphic amplification products indicate that these "pools" of elite germplasm are not distinct, and illustrate the relationships among individuals within and among groups of adapted clones. This material will be compared with samples from the world core collection and selected Manihot species, toward describing the distribution of genetic variability among the crops genetic resources