The effects of GA3 on the growth and antioxidant capacity of cucumber hypocotyls and radicles under sub-optimal temperature were investigated. The elongation of hypocotyls and radicles was significantly promoted by GA3 treatment under sub-optimal temperature, and the effects greatly depended on GA3 concentrations. In the previous reported investigation, there is not much information on the role of GA3 in modulating reactive oxygen species (ROS) under stress conditions, the present study indicated that GA3 treatment could decrease excess accumulation of ROS and alleviate lipid peroxidation which was induced by sub-optimal temperature in cucumber hypocotyls and radicles, the alleviating effects were highly correlated with the increasing activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) as well as antioxidative activity indicated as α,α-diphenyl-β-picryllhydrazyl (DPPH) scavenging activity, hydroxyl radical (âˆ™HO) scavenging activity and ferrous ion chelating activity. Furthermore, the increasing antioxidative activity was positively related with amylase activity in cucumber cotyledons, suggesting that the distribution of carbohydrate from cotyledons to hypocotyls and radicles might be responsible for higher antioxidant activity induced by GA3.
Key words: Cucumis sativus L., gibberellin, suboptimal temperature, hypocotyls, radicles, antioxidative activity.
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