Effects of Chilling Stress on the Activity of Ascorbic Acid Peroxidase and Glutathion Content in Cotyledons of Cucumber Seedlings
ZENG Shao-Xi, WANG Yi-Rou(South China Institute of Botany, Academia Sinica, Guangzhou 510650)
The effects of chilling stress on the activity of ascorbic acid peroxidase and GSH content in cucumber cotyledons were studied. The mechanism of oxygen toxicity in chilling injury as explored in this paper. The activity of ascorbic acid peroxidase and GSH content decreased with the severity ofchilling stress (Fig. 1) A negative correlation was found between the changes of enzyme activity and of GSH content, on the one hand, and the increase of electrolyte leakage and MDA content, on the other hand, in the cotyledons of cucumber seedlings under different low temperatures (Figs. 2, 3). The decrease of enzyme activity and GSH content induced by low temperature was enhanced by methylviologen (MV) and MDA pretreatment (Fig. 4, 5), but was reduced by sodium benzoate and α-tocopherol pretreatment (Fig. 6). The results indicated that an excess of active oxygen and MDA had toxic effects on ascorbic acid peroxidase and GSH.