Inhibition of betacyanin accumulation by abscisic acid in suspension cultures of Phytolacca americana

Abstract

Growth of cells and the accumulation of betacyanin were suppressed by the addition of abscisic acid (ABA) to suspension cultures of Phytolacca americana. The decrease in the accumulation of betacyanin was overcome by exogenously supplied tyrosine which is a precursor of betacyanin. ABA decreased the level of free tyrosine in the cells. Feeding experiments using labeled tyrosine revealed that ABA reduced the incorporation of labeled tyrosine into betacyanins (to about 50% of the control rate). These results suggest that both the availability of tyrosine and the biosynthetic activity of the pathway from tyrosine to the betacyanins are involved in the inhibition of the accumulation of betacyanins by ABA in Phytolacca americana cells.