Efficient Regeneration of Tetraploid Isatis indigoticaPlants via Adventitious Organogenesis from Hypocotyl Explants

An efficient in vitroplant regeneration system via hypocotyl segments of tetraploid Isatis indigoticaFort. was established. Murashige and Skoog's (MS) and Gamborg's (GB5) media were found to be superior to White medium for promoting shoot regeneration. The highest shoot regeneration (92 %) was achieved from hypocotyls cultured on MS medium containing 8.9 μM benzyladenine (BA) and 2.7 μM naphthaleneacetic acid (NAA), with an average of 4.2 shoots developed per explant. Plant regeneration was also improved when the explants were cultured in MS basal medium containing 3 % (m/v) sucrose and grown under a 12-h photoperiod. The developed shoots were well rooted in a half-strength MS medium supplemented with 0.5 μM indole-3-butyric acid (IBA) and were morphologically normal after transfer to soil.