Direct somatic embryogenesis in <i>Coffea arabica L. cvs.</i> Caturra and Catuaí: effect of tricontanol, light condition, and medium consistency

Abstract

The influence of triacontanol (TRIA) concentration and its interaction with indole-3- acetic acid (IAA) on direct somatic embryogenesis (DSE) of Coffea arabica L. cvs Caturra and Catuaí was determined. Additionally, light conditions and culture medium consistency (semisolid vs. liquid) were evaluated. A higher average of somatic embryos per explant from Caturra (3.9±0.5) and Catuaí (3.6±0.5) leaves was obtained when 4.55 μM TRIA was added to the half-strength Murashige and Skoog (1962) medium supplemented with 1.1 μM benzilaminopurine (BAP) and 2.85 μM IAA. In relation to medium consistency, the highest number of embryoids in Caturra (3.2±0.2) and Catuaí (6.0±0.4) explants was obtained using Yasuda et al. (1985) semisolid medium. Regarding photoperiod, the number of embryoids per explant obtained for Catuaí cultured under a 16 h light photoperiod was 7.6±1.0 and in the dark 6.2±0.6. In Caturra, 4.2±0.4 embryoids were produced in the dark and 3.8±0.5 with 16 h light. No somatic embryos were observed in Caturra and Catuaí explants after 12 weeks of culture in liquid Yasuda et al. (1985) medium, and under any of the light conditions.