optimizing in vitro regeneration of Hypericum (Hypericum perforatum L.)

Hypericum perforatum L. (St. John’s wort) has been received considerable interest worldwide due to its biochemical characteristics and unique secondary metabolites. In particular, aromatic polycyclic diones, such as hypericin and pseudohypericin have an interest as their antiviral, anticancer and antidepressant activities. To date, field grown plant material has generally been used for commercial St. John’s Wort production but the quality of these products may be affected by different environmental conditions, pollutants, fungi, bacteria, viruses, and insects which can alter the concentration of medicinal metabolite. In vitro systems have been reported as an effective tool for the development of genetically uniform plants. In order to approach optimal micropropagation of Hypericum perforatum, it will be necessary to optimize shoot proliferation stage in in vitro culture.
Material and In the present study, in vitro regeneration of Hypericum perforatum L. using different plant growth regulators on MS media has been developed. Callus was induced from leaves and shoots explants of St. Johns Wort on MS medium containing different levels of growth regulator (0, 2 and 4 mg/l BA; 1 and 2 mg/l Kin plus 0.1, 0.2 and 0.3 mg/l 2,4-D) in factorial experiment with completely randomized design in three replication. To shoot induction equal size of formed callus were separated and evaluated on MS media containing BA (0, 0.5 and 1 mg/l) and Kin (0, 0.5 and 1 mg/l). The shoot with terminal node were used on MS media containing IBA (0, 0.2, 0.4, 0.6, 0.8 and 1 mg/l ) to root induction.
After 4 weeks callus and shoot/root induction of explants were measured. Data analysis indicated that leaf explants produced higher callus mass than single node explant, also in leaf explants 2,4-D increment had no significant effect on callus mass induction while in single node, callus induction increased as 2,4-D increased. In presence of BA, callus induction from both explants increased with 2,4-D concentration raising. Single node explants produced highest mass of callus in media containing 2 mg/l BA plus 0.1 mg/l of 2,4-D. The highest number of shoots and the longest shoot achieved in presence of 1 mg/l BA with 0.5 mg/l Kin and 0.5 mg/l BA plus 1 mg/l Kin.
This experiment results revealed that different explants can be used to achieve high regeneration efficiency using different level of growth regulators. Also it seems that external growth regulators isnt essential lin Hypericum branch for rooting.