In vitro shoot Proliferation of Hypericum perforatum L. through Indirect and Direct Plant Regeneration

Hypericum perforatum L. (St. Johns’ wort) is the most commercially important species of the genus Hypericum and contains a wide range of components including naphthodianthrones, phloroglucinols, tannins, xanthones, phenolic acids and essential oil. In order to establish an efficient protocol for regeneration, the effects of explant type and plant growth regulators on direct and indirect shoot regeneration in H. perforatum were evaluated. According to obtained results the media supplemented with 0.1 mg l-1 Benzyl Adenine (BA) was effective for shoot proliferation from shoot tip explants of H. perforatum that showed the highest shoots number (15.5 shoots per explant) and shoot height (2.07 cm). In second experiment a method for rapid micro propagation of H. perforatum through indirect plant regeneration from calli has been developed. The results demonstrated that a combination of auxin and cytokinin was needed for optimum callus induction and leaf segments were suitable explant for callus induction in H. perforatum. Callus induction was observed in most studied treatments but the highest callus volume (1.43 cm3) was obtained by leaf segments in media supplemented with 0.25 mg l-1 2,4-Dichlorophenoxyacetic acid (2,4-D)+1 mg l-1 Kinetin. Successful shoot regeneration from callus was observed in MS medium containing 0.5 mg l-1 BA, which resulted the highest shoot proliferation rate (61.75%) and maximum number of induced shoots (9 shoots per explant). All of shoots formed root in media with 0.5 mg l-1 Indole-3-Butyric Acid (IBA) on which 100% of the regenerated shoots developed roots with an average number of 5 roots per shoot. The plantlets were acclimatized and transferred to the greenhouse with 80% survival. This in vitro propagation protocol should be useful for conservation as well as mass propagation of H. perforatum plant.