Effect of Plant Growth Regulators on Callus Formation, Plant Regeneration and Hypericin Production in Hypericum mysorense Hyne

摘要

Hypericum mysorense Hyne is a pharmaceutically important medicinal plant found in Western Ghats of India. In this study a new system was developed for in vitro plant regeneration through callus formation and hypericin production. Leaf explants were inoculated onto MS (Murashige and Skoog) medium supplemented with different concentrations and combinations of 6-benzyl adenine (BA), kinetin (KIN), alpha-naphthalene acetic acid (NAA) and 2,4-dichlorophenoxy acetic acid (2,4-D). Highest callus proliferation was observed when MS medium contained BA and NAA (1.0 mg/L each). Best shoot induction and multiplication was recorded on MS medium supplemented with 1.0 mg/L BA. A significant difference was recorded in average number and length of shoots/explant among the different concentrations of BA and KIN investigated. Roots were induced on MS media in the presence (0.5 mg/L) and absence of indole-3-acetic acid (IAA). Regenerated plantlets were successfully established in soil with a 98% survival rate. The concentration of hypericin was evaluated in different tissues of in vitro and ex vitro grown plants by using high performance liquid chromatography (HPLC) and thin layer chromatography (TLC). Hypericin levels were higher in callus (5.0 mu g/g, w/v) and leaves (4.1 mu g/g, w/v) of in vitro plantlets than those of ex vitro leaf samples (3.1 mu g/g, w/v). Results confirmed that plant growth regulators play an important role in the production of hypericin under controlled in vitro conditions. This is the firstever report on a rapid plant regeneration system for H. mysorense and provides an avenue for conservation strategies and phytomedicine production.