In vitro propagation of Digitalis lanata Ehrh. through direct shoot regeneration – A source of cardiotonic glycosides

Abstract

An efficient method for the in vitro propagation of Digitalis lanata Ehrh. through direct organogenesis from leaf and petiole explants has been standardised. MS basal medium supplemented with cytokinins BAP, KIN, TDZ either alone or along with auxins IAA and NAA at different concentrations were tried. TDZ at 4.54 and 6.81 μmol/l were optimum for direct regeneration of shoots from leaf (4.4 ± 0.6 shoots/explant), and petiole (3.0 ± 0.8 shoots/explant) explants respectively. Among the various concentrations of auxins IAA, IBA and NAA tried for rooting, the best response occurred on MS basal medium supplemented with 17.13 μmol/l IAA. On greenhouse transfer about 60% of the plantlets survived. In vitro raised plantlets were morphologically similar to mother plants. Cardiotonic glycosides digoxin and digitoxin were extracted by modified methods and estimated by HPLC. There were no significant differences in digoxin and digitoxin content in leaves of naturally grown and in vitro raised plants. The method for in vitro propagation of D. lanata through direct organogenesis from leaf and petiole explants reported here will be of great use for the rapid and large scale clonal propagation, production of biomass for extraction of cardiotonic glycosides, ex situ conservation, and improvement through conventional plant breeding and transgenic methods.