Callus induction and plant regeneration in Alternanthera philoxeroides

To establish a successful in vitro plant regeneration system in Alternanthera philoxeroides (Mart.) Griseb, an orthogonal design was used to investigate the effects of three factors (plant growth regulators, explant types and dark treatment in initial-stage), each having three levels. The effects of these factors and levels on callus induction and shoot regeneration were quantitatively evaluated by analysis of variance. The experimental results showed that the callus induction was significantly affected by 2, 4-dichlorophenoxyacetic acid (2, 4-D), and shoot differentiation from subcultured pieces of callus was enhanced mostly by dark treatment in initial-stage. The optimal conditions for callus induction are obtained from the stem explants cultured on semi-solid Murashige and Skoog (MS) medium plus 2.2 mu M BA and 2.2 mu M 2, 4-D, with 20 days dark treatment in initial-stage. The highest frequency of shoot regeneration is obtained from the calli cultured on semi-solid MS medium plus 8.8 mu M BA, without dark treatment in initial-stage.