Micropropagation to Conserve the Endangered Gabal Elba Dragon Tree (Dracaena ombet Heuglin ex Kotschy & Peyr)

Abstract

Plant tissue culture offers opportunities for the rescue and conservation of endangered plant species. Here, we report the successful in vitro propagation of Dracaena ombet, an endangered plant. Several physical and chemical seed treatments were evaluated to develop a propagation approach. Germination of D. ombet seeds was monitored for 16 weeks by placing them onto Murashige and Skoog (MS) medium. Maximum seed germination (20%) was recorded when seeds were soaked-scarified, whereas all other treatments did not result in seed germination. Fragmented (longitudinally bisected) and intact in vitro shoots were cultured onto MS medium supplemented with various concentrations of 6-benzylaminopurine (BAP) and indole butyric acid (IBA) to induce axillary shoots. Longitudinal fragmentation of explants had a greater effect than the intact explants for shoot proliferation when cultured onto medium containing plant growth regulators. Fragmented shoots cultured onto MS medium supplemented with 2 mg·L−1 BAP and 0.5 mg·L−1 IBA treatment resulted in the highest amount of axillary shoots (seven shoots per explant). The intact shoots had the highest axillary shoots (1.8 shoots per explant) when cultured onto a medium supplemented with a combination of 1 mg·L−1 BAP and 0.5 mg·L−1 IBA. One hundred percent rooting was obtained using half strength MS medium supplemented with 0.5 or 1 mg·L−1 IBA. With full strength MS medium, a maximum rooting of 60% was obtained with 1 mg·L−1 IBA or naphthalene acetic acid (NAA) addition. The plantlets were acclimatized to ex vitro conditions with a 95% survival rate. This study offers a simple method for in vitro propagation of D. ombet, which is valuable to enable conservation of this endangered species.