Exogenous paraquat changes antioxidant enzyme activities and lipid peroxidation in drought-stressed cucumber leaves |
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| Authors: | Zhong-Jing Liu Xiao-Long Zhang Ji-Gang Bai Bang-Xia Suo Pei-Lei Xu Lin Wang |
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| Institution: | 1. State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai’an 271018, Shandong, PR China;2. Beijing Entry-Exit Inspection and Quarantine Bureau, Beijing 100029, PR China |
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| Abstract: | In order to examine whether paraquat modifies the functioning of antioxidants and oxidative stress levels in drought-stressed plants, a cucumber cultivar (Cucumis sativus cv. Yuexiu no. 3) was grown hydroponically for 2 days. Drought stress, which was induced by polyethylene glycol (PEG), increased the contents of malonaldehyde (MDA), superoxide radical (O2−) and hydrogen peroxide (H2O2) in cucumber leaves, while pretreatment of paraquat decreased them. Under drought stress induced by PEG, we observed the decreased contents of MDA, H2O2 and O2− in paraquat-pretreated plants in comparison to unpretreated stressed plants. Drought stress and paraquat both increased the activities of antioxidants such as superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), guaiacol peroxidase (GPX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), dehydroascorbate reductase (DHAR, EC 1.8.5.1), monodehydroascorbate reducatase (MDHAR, EC 1.6.5.4), glutathione reductase (GR, EC 1.6.4.2), reduced glutathione (GSH) and reduced ascorbate (AsA). But the combined effect of paraquat application and drought stress resulted in the highest activities of antioxidants. So paraquat is able to moderate the activities of scavenging system enzymes and to influence oxidative stress intensity under drought stress induced by PEG. |
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| Keywords: | APX ascorbate peroxidase AsA reduced ascorbate CAT catalase DHAR dehydrateascorbate reductase GPX guaiacol peroxidase GR glutathione reductase GSH reduced glutathione GSSG oxidized glutathione H2O2 hydrogen peroxide MDA malonaldehyde MDHAR monodehydroascorbate reducatase O2&minus superoxide radical PEG polyethylene glycol PQ paraquat ROS reactive oxygen species SOD superoxide dismutase |
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