Effects of 24-epibrassinolide on antioxidation defense and osmoregulation systems of young grapevines (V-vinifera L.) under chilling stress

The objective of this study was to investigate the influence of exogenous 24-epibrassinolide (EBR) on the substances involved in antioxidation and osmoregulation responses of young grape plants under chilling stress. The grapevine leaves were sprayed with 0 (control), 0.05, 0.10 or 0.15 mg/L of 24-epibrassinolide and then exposed to 4 and 0 A degrees C for 24 h, respectively. The EBR treatment significantly enhanced the activities of antioxidative enzymes such as catalase, superoxide dismutase, peroxidase and ascorbate peroxidase in the plant leaves compared with the control. The contents of ascorbic acid and reduced glutathione increased after the EBR treatment, while reactive oxygen species (ROS) and lipid peroxidation were inhibited. In addition, the EBR treatment also greatly increased the contents of free proline, soluble protein, and soluble sugar. These results indicated that exogenous EBR treatment could enhance the antioxidation defense system and reduce oxidative damage caused by ROS and lipid oxidation in the young grapevine leaves. Meanwhile, it was found that the treatment could also increase the osmoregulation substance content in the grapevine leaves and improve their resistance against chilling stress.