Abstract
Pondweed (Potamogeton distinctus A.Benn.) is a monocotyledonous aquatic plant. The turions (overwintering buds) elongate with active glycolysis. Significant decreases in starch and amyloplast contents in anoxic turions showed that starch is the main source of energy. Although total activities of α-amylase and phosphorylase were not increased, an isozyme of each enzyme separated by native-PAGE remained active under anoxia. Especially the activity of a plastidic phosphorylase was significant under anoxia.
Changes in sucrose content and the activities of enzymes involved in synthesis or degradation of sucrose suggested that turnover of sucrose in anoxic turions is enhanced. The activity of sucrose synthase (SuSy) was significantly enhanced under anoxia. The gene encoding SuSy, which has high homology with that of Sh1 from maize, was expressed under anoxia, suggesting that this SuSy plays an important role in sucrose metabolism under anoxia.
