Efficient shoot organogenesis in petioles of yam (Dioscorea spp)

Shoot organogenesis was successfully achieved in petiole explants excised from 6 to 8-week old in vitro plantlets of yam Dioscorea rotundata P. cv. Kponan fissa, Dioscorea cayenensis L. cv. Krengle IB14 and cv. Krengle IB35, and Dioscorea alata L. cv. Bete bete. Only the basipetal portion of the petiole acquired competence, and plants regenerated within 21 days on MS medium supplemented with 2 % sucrose, 100 mg/l myo-inositol, 10 μM kinetin and 1.5 mM putrescine referred to as yam regeneration medium (YRM). Plant regeneration was significantly (p < 0.01) higher (42 %) with 2 % sucrose compared to 1, 3 and 4 % sucrose which produced 4, 25 and 15 % regeneration respectively. The age of the donor yam plantlet was critical to regeneration, and the highest regeneration efficiency was obtained with explants from 8-week old plantlets. Addition of the antioxidants lipoic acid (19.4 μM), and l-cysteine (28.5 μM) to the culture medium stimulated axillary branching in regenerated shoots. Among the four yam cultivars tested, cv. Kponan fissa, cv. Krengle IB14 and cv. Bete bete had similar response at 10 μM kinetin, while the cv. Krengle IB35 regenerated best at a lower concentration of kinetin (0.5 μM).