Embriogênese somática indireta em explantes foliares de Coffea arabica L. CV. Obatã

Abstract

It was aimed with this work to study the indirect somatic embryogenesis in Coffea arabica L. cv. 'Obatã', including the steps of induction, differentiation and regeneration of plants. Leaf segments withdrawn from plants under field conditions were disinfected with 70% alcohol for 1', 1% sodium hypochlorite for 15'and inoculated in 'CI' medium (callus induction) supplemented with 2,4 D (0, 1, 2 and 4 mg.L-1) and kinetin (0, 2, 4 and 8 mg.L-1). Later, the callus were transferred to the 'CD' medium (callus differentiation) to which was added 2,4-D (0, 1, 2 and 4 mg.L-1) and BAP (0, 2, 4 and 8 mg.L-1). During the regeneration step, friable embryogenic callus were inoculated in 'R' medium supplemented with BAP (0, 2, 4 and 6 mg.L-1) and sucrose (0, 15, 30, 45 and 60 g.L-1). The culture media utilized had their pH adjusted to 5.6 ± 1 before being autoclaved. The experiments were kept in growth room at 26 ± 1ºC. Over the steps of callus induction and differentiation, the experiments were carried out in dark conditions and at the regeneration step the experiments were carried out under 16-hour photoperiod and light intensity of 35 µmol.m-2.s-1. It was observed that the combination of 2,4-D and kinetin favors the induction of primary callus. High frequency of friable embryogenic callus was observed with BAP (8 mg.L-1), combined or not with 2,4-D, and greater number of embryos per explant, when sucrose (30g.L-1) and BAP (3 mg.L-1) was utilized.