First intergeneric hybrids (Psilanthus ebracteolatus Hiern x Coffea arabica L.) in coffee trees
Intergeneric hybrids between Psilanthus ebracteolatus (2n = 22) and Coffea arabica (2n = 44) were successfully produced by crossing at the tetraploid level. Although a total of 41 plants was obtained, only nine plants survived after 5 months growth in the nursery. Hybrid status was confirmed by means of cytological and molecular methods. For most of the morphological characteristics analyzed, hybrids appeared intermediate between the two parental species. The mean production of two surviving hybrids per 100 pollinated flowers as well as their fertility are comparable with those reported for intrageneric crosses between subgenera Coffea species, and do not support the present division of coffee trees into two genera. Both the capacity of C. arabica to hybridize with P. ebracteolatus and the fertility of hybrids produced appear high enough to envisage intergeneric gene transfers from P. ebracteolatus into C. arabica.Key words: coffee, fertility, hybridization, intergeneric, polyploid, wide cross.