Higher production of forskolin in genetically transformed cultures of Coleus forskohlii briq induced by growth regulators

Increased forskolin yield was obtained in transformed root, rhizogenic calli and cell suspension cultures of Coleus forskohlii when treated alone with various concentrations of auxins (IAA, IBA, NAA, 2,4-D), auxin conjugates (lAA-ala, lAA-gly, lAA-phe, lAA-asp), cytokinins (Kn, BAP) and gibberellic acid (GA₃) An 8.9-fold stimulation in forskolin production was achieved in transformed rhizogenic line GCO-RCH-10 in presence of 1.0 mg l⁻¹ GA₃, 6-fold in cell suspension line GSO-5/7-k in presence of 2 mg l⁻¹ BAP and 4.3-fold in root line RC-ST-2/16 in presence of 0.5 mg M GA₃ at the end of a culture period of 4 weeks. Growth and morphology was found to be influenced by the growth regulators studied. A seven fold increase in biomass was obtained in rhizogenic line GCO-RCH-10 with 0.5 mg l⁻¹ GA₃. In root line RC-ST-2/16, different concentrations of IAA, IAA conjugates and GAS stimulated growth while cytokinins inhibited growth of roots. The shoot culture line ST-2/51/d, showed prolific growth in the presence of all cytokinins but no forskolin was detected in the shoot cultures treated with any of these hormones.