An Efficient Micropropagation System for Morinda officinalis How. (Rubiaceae), an Endangered Medicinal Plant

Abstract

The present work developed an efficient plant regen eration and propagation system via direct organogenesis for Morinda officinalis How., a valuable endangered medicinal plant. The effects of explant types on shoot induction, pl ant growth regulators on shoot proliferation and elongation and the subsequent rooting ability of sh oots were examined. Among the various types of explant, direct shoot pr oliferation was successfully achieved from shoot tips and nodal stem segments with around 95% of the explants producing approximately 5 shoots per explant after 8 weeks of culture on optimal medium. On the other hand, leaf and internodal explants did not pr oduce any shoots. The most effective cytokinin on shoot proliferation was 6-benzyladenin e. When the concentration of 6- benzyladenine was at 1.0-2.0 mg L -1 , a high mean shoot number (about 5 shoots per explant) was achieved. Shoot elongation was obtaine d satisfactorily by transferring the shoots to Murashige and Skoog basal media containin g 2.0-3.0 mg L -1 gibberellic acid-3 within 2 weeks. Rooting was 100% on half-strength Murashige and Skoog medium containing 0.2 mg L -1 indole-3-butyric acid after 3 weeks of culture. Th e plantlets were acclimatized in the greenhouse and subsequently tra nsferred to the field with 90% survival rate. Keywords: Direct regeneration, Explants, Plant growth regula tors.