In vitro regeneration of Echinacea purpurea L.: Enhancement of somatic embryogenesis by indolebutyric acid and dark pre-incubation

Abstract

The embryogenic potential of different Echinacea purpurea tissues, viz. leaf, cotyledon, and root, was investigated. Maximum embryo-induction was achieved from leaf dises cultured on Murashige and Skoog medium supplemented with benzylaminopurine (5.0 μM) and indolebutyric acid (2.5 μM) where 95% of the explants responded, yielding an average of 83 embryos per explant within 4 wk of culture. Incubation of cultures in the dark for an initial period of 14 d significantly increased the frequency of somatic embryogenesis (6–8-fold in leaf explants). Exposure of the abaxial surface of leaves to the medium significantly increased the number of embryos. Transfer of somatic embryos to a medium devoid of growth regulators resulted in 80% germination within 7 d. Over 73% of the somatic embryos developed roots within 28 d of culture on a medium containing naphthaleneacetic acid (10 μM) with a maximum root number of 9.8 per plantlet. Transplanting ex vitro and acclimatization for a period of 7 d were sufficient to promote establishment of plants in the greenhouse, and more than 90% of the regenerated plants survived.