Efficient plant regeneration in vitro from red leaf beet via organogenesis

An efficient system for in vitro regeneration of red leaf beet, a variety of leaf beet (Beta vulgaris L. var cicla L.) generally used to decorate parterre and to prepare betacyanin, was developed for the first time in the present study. Shoot tip and petiole explants from the sterile seedlings, precultured on Murashige and Skoog (MS) medium with 15 mg/l 6-benzyladenine (BA) and 3% sucrose at 16 °C for 30 days, could form 81.02 and 17.33% translucent nodular (TN) calli, respectively. All TN calli were able to differentiate into adventitious shoots under the same culture conditions. Each explant with TN callus from the shoot tip and petiole could generate 8.65 shoots on average. It was found that both preculture of sterile seedlings and culture of explants at low temperature (16 °C) were vital for TN callus induction and adventitious bud formation of red leaf beet. The best condition for rooting was 0.5-strength MS medium with 10 g/l sucrose. After being transplanted into soil, plantlets grew well and could flower and bear fruits. Histological observation revealed that TN callus was derived from the cells of vascular tissue of the petiole and that adventitious shoots were formed through organogenesis. The factors influencing in vitro micropropagation are also discussed.