Full Length Research Paper

Gibberellin A₃ pretreatment increased antioxidative capacity of cucumber radicles and hypocotyls under suboptimal temperature

Qingzhu Li¹, Chaohan Li¹, Xianchang Yu² and Qinghua Shi¹*

¹State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai’an 271018, China.

²Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.

*Corresponding author. E-mail: qhshi@sdau.edu.cn .

Accepted 21 June, 2011

 Abstract

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 (∙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.