Gibberellin-induced changes in glycolysis and in lipid metabolism of wheat leaves

Abstract

Chromatographic analysis of wheat leaves grown for 4 to 10 days in a solution of gibberellic acid (10–20 p.p.m.) revealed a higher level of fructose-1,6-diphosphate as compared with that of 3-phosphoglyceric acid and phosphoenolpyruvic acid, and of 3-phosphoglyceric acid as compared with that of a hitherto unidentified phosphate. These changes were found under different light regimes which preceded extraction of phosphates from leaves. On the basis of these data and in view of earlier results (Lustinec, Pokorna, Růžicka 1962) it is assumed that glycolysis interacts with reactions utilizing its intermediate products for the synthesis of lipids, this representing a possibility of bringing about changes in leaf phosphate levels due to gibberellic acid. In order to verify the postulate the incorporation of 1-14C- and 6-14C-glucose into lipids, phospholipids (the magnesium salts of which are insoluble in acetone), carbon dioxide and the non-lipid fraction of leaves was investigated. It appeared that the incorporation of 1-14C into the lipid fractions of plants grown for 3–7 days in a gibberellic acid solution is markedly lower than that of 6-14C. The ratio of radioactivities C6∶C1 was increased in the lipids by the three-hour treatment of leaves with gibberellic acid (10 and 50 p.p.m.) during their incubation with glucose-14C. In view of the fact that the amount of substances extractable with ether is the same in the experimental and in the control leaves and that the incorporation of 1-C into lipids is frequently considerably higher in the controls than the incorporation of 6-C the effect of gibberellic acid on the rate of exchange of carbon atoms between the lipids and the products of glucose catabolism should be borne in mind.