Optimization of somatic embryogenesis in coffea canephora

Plant tissue culture allows the clonal propagation of Coffea canephora on a large scale through somatic embryogenesis. The aim of this study was to optimize the conditions for the induction of somatic embryogenesisin leaves of the Robusta variety. The physiological stage of the leaves – drain or source; the use of the surrounding area ofprimary or secondary veins; and the position of the explants – abaxial or adaxial surface in contact with the culture medium were evaluated. The explants were inoculated in a modified MS culture medium (1/2 macro, 1/4 micronutrients), supplemented with 30 g L-1 sucrose, 6 g L-1 agar, 1.0 mg L-1 2iP and 5.0 mg L-1 IBA. At 45 days of culture, the occurrence of callus induction and the dry weight of the explants were evaluated and, at 120 days, the average number of cotyledonary embryos per explant. The leaf fragments most responsive to the induction of somatic embryogenesis were taken from drain leaves, with explants containing secondary veins, placed with the adaxial face in contact with the culture medium.