Genetic diversity of wild coffee (Coffea arabica L.) using molecular markers

Genetic diversity was studied using RAPD markers among 119 coffee (Coffea a rabica L.) individuals representing 88 accessions derived from spontaneous and subspontaneous trees in Ethiopia, the primary centre of species diversi ty, six cultivars grown locally in Ethiopia, and two accessions derived fro m the genetic populations Typica and Bourbon, spread in the 18(th) century, which gave rise to the most currently grown cultivars. Twenty-nine polymor phic fragments were used to calculate a similarity index and construct dend rograms. The Ethiopian material was separated from the Typica- and Bourbon- derived accessions and classified in four groups: one with most of the coll ected material from southwestern Ethiopia and three from southern and south eastern Ethiopia. Almost all detected diversity was found in the southweste rn group while the southern and southeastern groups presented only 59% of i dentified markers. The genetic distances were low between the southwestern group and the southern and southeastern groups, and between the southwester n group and the Typica- and Bourbon-derived accessions. The cultivated coff ee derived from the genetic populations Typica and Bourbon appeared little differentiated from wild coffee growing in the southwest. The results suppo rted the hypothesis that southwestern Ethiopian coffee trees could have bee n introduced recently in the south and southeast. A separate analysis of th e 80 accessions classified in the southwestern group allowed identifying pa rticular spontaneous- and subspontaneous-derived accessions and redundancie s in the collected material from southwestern Ethiopia. RAPD markers did no t detect any within-collection polymorphism except for two trees that were identified as off-types in the CATIE field genebank.