Rooting and acclimatization of micropropagated Hypericum perforatum L. native to Sicily

Abstract

Hypericum perforatum L. is traditionally used as a medicinal plant because of its different bioactive compounds with documented antidepressant and antiinflammatory activities. Plantlets’ mass production with high content of these secondary metabolites has been enhanced through in vitro culture but the process has often been stopped at the multiplication phase. A study was conducted in order to set up an efficient in vitro rooting and acclimatization protocol of a H. perforatum Sicilian genotype well-adapted to south Mediterranean conditions. Aseptic nodal segments were cultured onto a Murashige and Skoog (MS) basal medium supplemented with 4.44 µM 6-benzyladenine for multiplication. Microshoots were then transferred onto specific culture media for in vitro rooting in order to evaluate the nutrients concentration and different auxins effect: full and half-strength hormone-free MS or supplemented with 5.7 µM indole-3-acetic acid (IAA) or 4.9 µM indole-3-butyric acid (IBA). Highest rooting rate was achieved on full-strength MS with IAA 5.7 µM and on all half-strength MS media; higher number of roots was recorded on half-strength MS with IAA and full-strength MS with IBA 4.9 µM; longest roots were measured on full-strength MS with IAA 5.7 µM. Rooted plantlets were ex vitro acclimatized by transferring them into greenhouse in plastic pots filled with peat: perlite and sand: perlite mixtures (1:1, v/v) under mist: acclimatization rate was higher for rooted plantlets grown in sand:perlite substrate.