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| Effects of Exogenous Calcium on Oxidative Responses and Nitric Oxide in Chinese Cabbage（Brassuca pekinensis） Under Cadmium Stress |
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| KeyWord:cadmium stress; calmodulin; antioxidant enzymes; reactive oxygen species; nitric oxide |
| Author Name | Affiliation | | LIN Xiao | Landscape Architecture College of Sichuan Agricultural University, Chengdu 611130, China | | GAO Su-ping | Institute of Landscape Architecture of Sichuan Agricultural University, Chengdu 611130, China | | LEI Ting | Landscape Architecture College of Sichuan Agricultural University, Chengdu 611130, China | | WANG Cheng-cong | Landscape Architecture College of Sichuan Agricultural University, Chengdu 611130, China | | ZHANG Kai-hui | Landscape Architecture College of Sichuan Agricultural University, Chengdu 611130, China |
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| Abstract: |
| Calcium can alleviate heavy metal stresses in plants. A hydroponic experiment was conducted to investigate the physiological mechanisms of Chinese cabbage（Brassuca pekinensis） responses to cadmium（Cd） stress under exogenous calcium（Ca）. Concentrations of Ca and Cd ions, reactive oxygen species（ROS）, malondialdehyde（MDA）, glutathione, and endogenous nitric oxide（NO） as well as antioxidant enzymatic activities in cabbage leaves were determined. Meanwhile, the transduction function of Ca2+-CaM influenced by Trifluoperazine（TFP, 0.2 mmol·L-1） was also investigated. Cadmium stress decreased Ca concentrations in cabbage leaves, while exogenous Ca addition increased Ca but decreased Cd concentrations in the leaves. However, TFP had no significant effects on the concentrations of Ca and Cd. Cadmium induced ROS outburst in cabbage leaves, resulting in the peroxidation of plasmalemma and also suppressed superoxide dismutase（SOD） activity. However Cd increased the activities of ascorbate peroxidase（APX）, catalase（CAT）, and peroxidase（POD） and the concentration of clutathione（GSH）, causing an escalated peroxide pressure in cabbage leaves. Exogenous Ca addition alleviated Cd induced pressure, but such alleviating effect was weakened by TFP addition. Nitric oxide concentrations in cabbage leaves were reduced by Cd but increased by exogenous Ca. This boosting effect of Ca was depressed by TFP addition. These results suggest that exogenous Ca reduces the Cd stress in cabbage leaves through decreasing Cd uptake and increasing antioxidant capability by Ca2+-CaM signal pathway. |
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