Though 2,4-D (4.5 μM) and BA (8.8 μM) stimulated the formation of two kinds of calluses showing different morphologies; one of them with nodular structures could be related with embryogenic callus formation. Michelangeli de Clavijo et al. [38] reported in Bixa orellana L. cultures, proembryos (nodular structures), spherical structures, with cells of variable shape and size, originating from callus surface, after the initial stages globular and heart-shaped somatic embryos was observed.
Embryogenic callus induction and somatic embryo development from cotyledonary explants of T. erecta on 2,4-D (4.5 μM)/kinetin (0.93 μM) medium were reported previously by Bespalhok and Hattori .