Effects of soil cadmium on growth, oxidative stress and antioxidant system in wheat seedlings (Triticum aestivum L.).
Effects of different concentrations of soil cadmium (0-33mg kg(-1)) on growth, oxidative stress, and antioxidant response of wheat seedlings (Triticum aestivum L.) were investigated using pot experiments. A slight stimulatory effect on seedling growth was observed, especially at low Cd concentrations (less than 3.3mg kg(-1)). Results of the electron paramagnetic resonance (EPR) determination showed a decrease in unstable free radical level in the leaves, followed by a significant increase with increasing Cd concentrations. Malondialdehyde (MDA) contents were significantly enhanced by a high Cd concentration. Activity levels of some antioxidant enzymes in the leaves, including superoxide dismutase (SOD, EC1.12.1.1), catalase (CAT, EC1.11.1.6), guaiacol peroxidase (GPX, EC1.11.1.7), ascorbate peroxidase (APX, EC1.11.1.11) and glutathione reductase (GR, EC1.6.4.2), did not change much at low Cd concentrations (less than 3.3mg kg(-1)), but fluctuated drastically at high Cd concentrations. GSH contents and GSH/GSSG ratios decreased at low Cd concentrations, then increased at high Cd concentrations. Wheat seedlings might overcompensate at low Cd concentrations, resulting in a low oxidative stress and a positive effect on growth. Changes in biochemical parameters would occur before any visible symptom of toxicity appeared, and the endpoint based on these parameters might be more sensitive or indicative than morphological observations in revealing the eco-toxicity of Cd. Based on the results of this study, we propose that the toxic critical value of soil Cd in inducing oxidative stress to wheat seedlings is between 3.3mg kg(-1) and 10mg kg(-1).
Lin
Renzhang
R
State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210093, China.
Wang
Xiaorong
X
Luo
Yi
Y
Du
Wenchao
W
Guo
Hongyan
H
Yin
Daqiang
D
D000975:Antioxidants / Q000378:metabolism; D002104:Cadmium / Q000633:toxicity*; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D012989:Soil Pollutants / Q000633:toxicity*; D014908:Triticum / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
D000975:Antioxidants; D012989:Soil Pollutants; D002104:Cadmium; D010088:Oxidoreductases; D005978:Glutathione; D019803:Glutathione Disulfide