CALCIUM RESTRICTION INDUCES CARDENOLIDE ACCUMULATION IN CELL-SUSPENSION CULTURES OF DIGITALIS-THAPSI L

The removal of calcium ions from Murashige and Skoog culture medium in duced a marked increase in the accumulation of cardenolides in cell su spension cultures of Digitalis thapsi. Cell viability was not affected although growth was slightly reduced. Strontium ions could substitute for calcium in inhibiting cardenolide production, this effect of calc ium being reversed by the addition of LaCl3 or ethyleneglycol-bis-(bet a-aminoethyl ether)-N,N'-tetraacetic acid. The results suggest that ca lcium, apart from its general effects on growth, may play a role in th e regulation of cardenolide metabolism in a concentration dependent ma nner.