Indirect shoot regeneration of Iranian purple coneflower (Echinacea purpurea L.) from cotyledon and hypocotyl explants

Abstract

In vitro plant regeneration was optimized for Iranian purple coneflower via organogenesis from callus cultures derived from cotyledon and hypocotyl tissues by placing them on MS medium supplemented with different concentrations and combinations of BAP and NAA. The experiment was laid out as a completely randomized design in a factorial arrangement with three replications. The results indicated that the mean callus induction was influenced by explant type, with a significant difference between cotyledon (77.81%) and hypocotyl (65.33%) explants at the 0.01 probability level. In relation with the regeneration rate, no significant differences were observed between the two types of explants. For both cotyledons and hypocotyls the optimum shoot regeneration frequency (31.5% and 32.5%, respectively) and number of shoots per explant (5.2 and 5.3, respectively) were achieved using medium supplemented with 0.4 mg l−1 BAP. Proliferated shoots were elongated in hormone-free MS medium and well-developed shoots were rooted on MS medium, both with and without the addition of 2 mg l−1 IBA. All the plantlets survived acclimatization, producing normal plants under controlled conditions. This study revealed that cotyledon and hypocotyl explants of E. purpurea have relatively good potential for callus induction and shoot formation. Furthermore, a beneficial method has been established for the micropropagation of this valuable medicinal species.