An efficient and rapid plant regeneration system for sweet potato [Ipomoea batatas (L.) Lam.]

An efficient and rapid system was established for direct shoot regeneration from leaf explants of sweet potato [Ipomoea batatas (L.) Lam.]. Adventitious shoots were induced from leaf explants of cvs. 'Tainong (T) 5 7', 'T 64' and 'T 66' of sweet potato on modified MS medium [MS inorganic salts (MURASHIGE and SKOOG 1962), 0.6 mM myo-inositol, 5.0 mu M thiamine-HCl, 10.0 mu M nicotinic acid, 5.0 mu M pyridoxine-HCl (ZHENG et al. 1996)] supplemented with benzyladenine (BA), thidiazuron (TDZ), 2-isopentenyladenine (2ip) alone as well as TDZ in combination with indole-3-acetic acid (IAA). Type and concentrations of cytokinins influenced adventitious shoot induction. Among BA, TDZ and 2ip, TDZ was the best for adventitious shoot induction with an optimal concentration of 5.0 mu M (average of 73.6, 72 and 50.3 shoots were induced from 30 leaf explants of cvs. 'Tainong 66', 'T 64' and 'T 57', respectively). Adventitious shoot induction was not improved with the addition of IAA; however, it promoted elongation of shoots. In vitro grown shoots were rooted on MS medium alone and also on MS supplemented with IBA. The well developed plantlets were successfully acclimatized in growth chamber under controlled environmental condition. Hardened plants were transplanted to pots and maintained in green house. The survival rate of the plantlets was 86-95 %. This protocol of direct induction of adventitious shoots could be useful for the genetic transformation of sweet potato.