Efficient plant regeneration from embryogenic suspension cultures of sweetpotato

Using 15, Chinese and Japanese cultivars of sweetpotato, lpomoea batatas (L .) Lam., we succeeded in developing an efficient plant regeneration system from embryogenic suspension cultures. The embryogenic callus derived from s hoot apices of the 15 cultivars, was used to initiate embryogenic suspensio n cultures in Murashige and Skoog (MS) medium containing 9.05 muM 2,4-dichl orophenoxyacetic acid (2,4-D). Rapidly proliferating and well-dispersed emb ryogenic suspension cultures were established. Cell aggregates 0.7-1.1 min in size from embryogenic suspension cultures were transferred to. solid MS medium supplemented with 9-05 muM of 2,4-D and formed embryogenic, callus w ith somatic embryos. The embryogenic callus with somatic embryos was furthe r transferred to MS medium supplemented with 3.78 muM of abscisic acid, res ulting in the germination of somatic embryos. Within 20 wk after the initia tion, the frequencies of cell aggregates forming plantlets reached approxim ately 100% for the 15 tested cultivars. These plantlets, when transferred t o, soil, showed 100% survival. No morphological variations were observed.