Bioaccumulation and ROS generation in Coontail Ceratophyllum demersum L. exposed to phenanthrene

Phenanthrene bioaccumulation, induction free radicals and their consequent biochemical responses in coontail (Ceratophyllum demersum L.) were examined. Plants were exposed to different levels (0.01, 0.02, 0.05, 0.07 and 0.1 mg/l) of phenanthrene for 10 days. Results showed that the phenanthrene concentration in the plants was exponentially correlated to exposure concentration (R (2) = 0.958) and phenanthrene exposure significantly increased the total free radicals and superoxide anion in the plants. The activities of antioxidant enzymes and the contents of glutathione were determined. The superoxide dismutase (SOD) activity and reduced glutathione (GSH) content were inhibited, while the catalase (CAT), peroxidase (POD), glutathione-s-transferase (GST) activities and oxidized glutathione (GSSG) content were significantly induced. Changes in the contents of chlorophyll and malondialdehyde (MDA) indicated that the MDA content was enhanced after phenanthrene exposure and the contents of chlorophyll were significantly increased in the 0.01 mg/l group. These experimental data demonstrated that the bioaccumulation of phenanthrene induced the production of free radicals and ROS, and changed the antioxidant defense system, ultimately resulting in oxidative damage in C. demersum.