INHERITANCE OF CAFFEINE AND HETEROSIDE CONTENTS IN AN INTERSPECIFIC CROSS BETWEEN A CULTIVATED COFFEE SPECIES COFFEA-LIBERICA VAR DEWEVREI AND A WILD-SPECIES CAFFEINE FREE C-PSEUDOZANGUEBARIAE

Coffee species originating from Africa, in particular the two major cu ltivated species C. arabica and C. canephora, usually contain caffeine in their beans, whereas almost all Malagasy coffee species are caffei ne-free. However, one wild coffee species C. pseudozanguebariae, colle cted near the coast in south Kenya, is also caffeine-free. Beans of th is species contain a specific heteroside diterpene (hereinafter referr ed to simply as heteroside) and give a bitter coffee beverage. We have investigated the inheritance of the caffeine and heteroside contents in the first and second generations of an interspecific cross between C. pseudozanguebariae and C. libel ica var. dewevrei, for which the ca ffeine content is about 1% dmb (dry matter basis). The caffeine conten t of F-1 hybrids (0.2% dmb) was lower than the parental average (0.47% dmb). Caffeine and heteroside contents appeared to be under polygenic control with a strong genetic effect. Nevertheless, one major gene wi th two alleles seemed to be involved in the control of both compounds. Absence of caffeine was apparently controlled by one recessive gene. Heteroside content seemed to be controlled by one co-dominant gene, he terozygotes being intermediate between the two different groups of hom ozygotes.