Regeneration of the East African greenheart, Warburgia ugandensis (Sprague) through tissue culture

Warburgia ugandensis is a medicinal plant in the family Canellaceae. There has been a very high demand for Warburgia products for medicinal purposes leading to overexploitation. Warburgia also produces recalcitrant seeds, a fact that has hindered the natural regeneration of this species. In this study, clonal propagation was postulated to be an alternative to propagation through seeds. Shoot tip explant materials were obtained from glasshouse maintained seedlings and these were surface sterilized using both ethanol and sodium hypochlorite. Shoot proliferation and elongation was achieved on shoot tips cultured on full strength Murashige and Skoog (MS) medium containing 3% sucrose, 1.13 mg L super(-1) benzylamine purine (BAP) and 0.11 mg L super(-1) of kinetin (KIN). A combination of BAP and kinetin resulted in a significant (p< 0.01) shoot elongation (3.0 cm) and the number of shoots (4 shoots per explants) after 44 days. The best in vitro rooting (50%) was induced through 1 mg L super(-1) naphthalene acetic acid (NAA) on a half strength Gamborg's woody plant medium (WPM) containing 3% sucrose. These results indicate that W. ugandensis can be regenerated via in vitro culture using a combined BAP and kinetin to induce multiple shoots and subsequently rooting them under 1 mg/L NAA. The study has therefore developed a protocol for mass clonal propagation of this important medicinal tree.