Abstract:
An efficient and reproducible plant regeneration protocol for the South African sweet potato (Ipomoea
batatas Lam.) cultivar Blesbok was developed in this study. The effect of different hormone
combinations and type of explant on shoot regeneration was evaluated in order to optimize the
regeneration protocol. Explants in the form of stem sections, leaf discs, apical shoots and axillary buds
derived from in vitro stock plant cultures were cultured on Murashige and Skoog (MS) media
supplemented with 36 combinations of naphthalene acetic acid (NAA) (0, 0.01, 0.1, 0.2, 0.5, and 1 mg/L)
and 6-benzylaminopurine (BAP) (0, 0.01, 0.1, 0.2, 0.5 and 1 mg/L). The highest percentage of shoot
regeneration was obtained when apical shoot explants (31%) and axillary bud explants (22%) were
cultivated on MS supplemented with 0.01 mg/L NAA + 1 mg/L BAP. Leaf discs and stem section
explants produced highly recalcitrant callus that did not regenerate into shoots in shoot induction
medium (SIM). Callus from apical shoots explants cultured on SIM developed into shoots. The shoots
rooted readily on root induction medium (RIM) and then in hormone free MS medium. Regenerated
plants appeared normal and showed a 100% survival rate when transferred to soil. The regeneration
protocol described in this study will be used in a plant transformation protocol to produce transgenic
sweet potato with broad virus resistance
