Abstract
The present study reports a simple protocol for indirect shoot organogenesis and plant regeneration of Sutherlandia using rachis and stem segments. Different concentrations (0.0-68.08 mu mol l(-1)) of thidiazuron (TDZ) were used for callus induction and shoot organogenesis. The highest percentage of callus formation (97.5%) and the highest percentage of explants forming shoots (88.8%) were obtained from rachis explants cultured onto Murashige and Skoog (MS) medium (Murashige and Skoog, Physiol. Plant. 15:473-495, 1962) supplemented with 45.41 mu mol l(-1) TDZ. Scanning electron microscopy demonstrated the early development of adventitious shoots derived from callus cultures. Shoot clusters were further developed and grown in MS hormone-free medium. The presence of l-canavanine was determined by thin-layer chromatography and confirmed after column fractionation using silica gel and nuclear magnetic resonance spectroscopy. Individual shoots were rooted on different concentrations and combinations of MS salt strength and IBA. Half-strength MS salt medium supplemented with 24.6 mu mol l(-1) IBA was optimal for root induction in which 78% of shoots were rooted. The in vitro plants were successfully acclimatized in a growth chamber with a 90% survival rate.