Genetic diversity of wild and cultivatedCoffeacanephora in northeastern DR Congo and the implications for conservation

AbstractPremiseMany cultivated coffee varieties descend fromCoffea canephora, commonly known as Robusta coffee. The Congo Basin has a century long history of Robusta coffee cultivation and breeding, and is hypothesized to be the region of origin of many of the cultivated Robusta varieties. Since little is known about the genetic composition ofC. canephorain this region, we assessed the genetic diversity of wild and cultivatedC. canephorashrubs in the Democratic Republic of the Congo.MethodsUsing 18 microsatellite markers, we studied the genetic composition of wild and backyard-grownC. canephorashrubs in the Tshopo and Ituri provinces, and from the INERA Yangambi Coffee Collection. We assessed genetic clustering patterns, genetic diversity, and genetic differentiation between populations.Key resultsGenetic differentiation was relatively strong between wild and cultivatedC. canephorashrubs, and both gene pools harbored multiple unique alleles. Strong genetic differentiation was also observed between wild populations. The level of genetic diversity in wild populations was similar to that of the INERA Yangambi Coffee Collection, but local wild genotypes were mostly missing from that collection. Shrubs grown in the backyards were genetically similar to the breeding material from INERA Yangambi.ConclusionsMostC. canephorathat is grown in local backyards originated from INERA breeding programs, while a few shrubs were obtained directly from surrounding forests. The INERA Yangambi Coffee Collection could benefit from an enrichment with local wild genotypes, to increase the genetic resources available for breeding purposes, as well as to support ex situ conservation.