Cytokinin and explant types influence in vitro plant regeneration of Leopard Orchid (Ansellia africana Lindl.)

The effects of explant and cytokinin types on in vitro plant regeneration of Ansellia africana were investigated. The exogenous addition of cytokinins is not required for the proliferation of new protocorms from Trimmed protocorm cluster (TPC) explants. To the contrary, nodal and shoot-tip explants produced a single shoot in response to the addition of cytokinins. Overall plant growth in terms of shoot length, leaf number, frequency of root organogenesis, root length, and fresh weight/plant were significantly higher in media containing meta-Topolin Riboside (mTR) in both nodal and shoot-tip explants. Thidiazuron (TDZ) and 6-benzyladenine (BA) induced stunted and hypertrophied shoots at their highest level (15 mu M). In addition root differentiation and root growth were significantly lower on P668 media with TDZ and BA. Zeatin was capable of inducing a significantly higher root organogenesis frequency and root length in TPC explants as compared to other cytokinins. However, TPC explants produced a significantly greater number of longer shoots (> 3 cm) on P668 media with mTR. Hyperhydric shoots were produced from TPC explants. The occurrence of hyperhydricity is discussed with respect to the culture vessel used in this study.