Effect of gibberellin on protein and non-structural carbohydrate in dormant Avena fatua caryopses

Application of gibberellic acid (GA₃) to dormant Avena fatua L. caryopses resulted in the termination of dormancy within 24 h as indicated by germination between 24 and 48 h. During the period of imbibition from 0 to 24 and 24 to 48 h changes occurred in protein and carbohydrate metabolism in GA-treated and untreated caryopses. Germination did not occur in untreated caryopses, therefore physiological changes in these caryopses were not associated with the termination of dormancy. GA-treatment increased the concentration of soluble and SDS-extractable protein in the endosperm tissue by 4 and 5%, respectively, over the 24 h untreated material; no changes were apparent when the protein profiles of GA-treated and untreated tissues were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) 0, 24 and 48 h after imbibition. The concentration of hexose and sucrose in the GA-treated endosperm tissue increased 189 and 151 μmol, respectively, over the untreated material at 24 h. Gibberellic acid had no effect on starch metabolism in the endosperm tissue in the first 24 h, the period associated with the termination of dormancy. The concentration of hexose increased by 57 μmol and starch decreased by 80 μmol in the GA-treated embryo tissue within 24 h. Our results demonstrate that exogenously applied GA influences sucrose and hexose metabolism in the endosperm tissue. The specific effect of GA on starch and hexose metabolism in the dormant A. fatua caryopsis embryo tissue may be associated with the termination of dormancy.