SOMATIC EMBRYOGENESIS IN Heliconia collinsiana GRIGGS

Abstract

Heliconias are ornamental tropical plants highly appreciated for their inflorescences with exotic shapes and bright colors. Its cultivation requires propagation systems such as somatic embryogenesis that allow the cloning of elite genotypes for generation of sufficient vegetative material of certified phytosanitary quality. The objective of this research was to establish a somatic embryogenesis protocol for Heliconia collinsiana and histologically characterizing the origin of the embryos. Cross-sections from the base of pseudostems of in vitro plants regenerated were established in Murashige and Skoog (MS) medium with different concentrations of 2,4-diclophenoxyacetic acid (2,4-D) to induce callus formation. The effect of benzyladenine (BA) and abscisic acid (ABA) was evaluated at maturation and germination stages of embryos, and the concentration of MS salts was evaluated at the time of conversion to plants. Callus formation occurred in the dark with 18 mg L^-1 of 2,4-D and 0.5 g L-1 of activated charcoal. Callus multiplication was obtained with 1 or 2 mg L^-1 of 2,4-D and 16 h light. Maturation and germination of the somatic embryos was observed with 0.5 mg L^-1 of BA and conversion and growth of the plants was achieved with half the salts concentration in the MS medium. Embryos originated from proembryogenic masses composed of small, isodiametric cells with prominent nuclei and dense cytoplasm. At the acclimatization stage, 95 % of the plants survived under greenhouse conditions. This is the first novel somatic embryogenesis protocol for clonal multiplication of this ornamental species and establishes the base for future studies in other native species, commercial cultivars or hybrids derived from genetic improvement.