ABSTRACT
A series of experiment were conducted using leaf and cotyledon explants of African Yam Bean (Sphenostylis stenocarpa (Hocst ex. Rich) Harms) to assess the optimal growth condition for callus development using Murashige and Skoog (MS) medium. The explants used consisted of 14day old seedling germinated in-vitro on magenta plastics from which the leaves were excised , and cotyledons were soaked in distilled water for 20minutes and decoated. Both explants were cultured on MS medium supplemented with auxins (2,4-D, TDZ and NAA) and cytokinins (Kinetin, BAP and 2ip) under continuous light for 28days. Callus initiation were optimal for cotyledon explants at 0.25mg/l 2,4-D in combination with 2.0mg/l Kinetin, and 0.25mg/l 2,4-D, 2.0mg/l Kinetin and 0.5mg/l NAA. However, for leaf explants there was no response across the concentrations and the leaves withered. The MS media supplemented with 0.25mg/l 2,4-D, 2.0mg/l Kinetin and 0.5mg/l NAA gave a better response compared to 0.25mg/l 2,4-D in combination with 2.0mg/l Kinetin. The calluses obtained were transferred to another set of 5 culture MS media supplemented with combination of 2.0mg/l 2,4-D and 1.5mg/l TDZ, 0.1mg/l 2iP and 0.5mg/l NAA, 1.0mg/l NAA and 0.2mg/l BAP, 0.1mg/l 2,4-D and 2.0mg/l BAP, and 0.1mg/l NAA and 0.4mg/l KIN for further callus development. The calluses were observed to increase in size. Further studies are suggested, however, to optimize somatic embryogenesis from the leaf and cotyledons explants for clonal propagation and biotechnology applications.
