Regulation of potato tuber protein accumulation by gibberellic Acid.

Many studies have shown that gibberellic acid (GA(3)) inhibits tuberization in potato (Solanum tuberosum L.). In this study, we have utilized the 40 kilodalton glycoprotein, patatin, as a marker for biochemical events associated with the process of tuberization. To determine the effects of exogenous applications of GA(3) on the induction of the accumulation of this major tuber protein, we measured patatin levels in tubers from treated whole plants, petioles from a single-node cutting system with GA(3) applied in a lanolin paste, and stolon tips cultured in vitro on an inductive medium supplemented with GA(3). In all three systems, GA(3) inhibited the accumulation of patatin and the major 15 and 22 kilodalton tuber proteins. This effect appeared to be selective since most of the other proteins were not affected and, in tubers, at least one protein was stimulated by GA(3). These results suggest that GA(3) can reverse biochemical events of tuberization in tubers as well as prevent the accumulation of the major tuber proteins in other inducible tissues.