EFFECTS OF GIBBERELLIC-ACID ON MORPHOGENESIS AND CARDENOLIDE ACCUMULATION IN JUVENILE AND ADULT DIGITALIS-OBSCURA CULTURES

Effects of gibberellic acid on morphogenesis and cardenolide accumulat ion in in vitro cultures of Digitalis obscura are reported. Cultures w ere established from hypocotyls or leaves of axenic seedlings and shoo t tips of mature plants. Irrespective of the kind of explant, gibberel lic acid by itself did not induce morphogenesis but modified those mor phogenic responses promoted by auxins and/or cytokinins, always inhibi ted organogenesis and favoured both embryo formation and conversion in to plants. Gibberellic acid did not significantly affect cardenolide c ontent of plants regenerated from juvenile or mature D. obscura explan ts.