Effects of bisphenol A on antioxidant system in soybean seedling roots

Bisphenol A (BPA), an emerging pollutant in the environment, has potential toxic effects on plants. The toxicity mechanism, however, remains largely unknown. The antioxidant system plays an important role in protecting plants against the damage of stress. The present study investigated the effects of BPA on the antioxidant system (superoxide dismutase [SOD], peroxidase [POD], catalase [CAT], ascorbic acid [AsA], proline, reduced glutathione [GSH]), reactive oxygen species (ROS; hydrogen peroxide [H2 O2 ], superoxide anion [O2 (-) ]) accumulation, and membrane lipid peroxidation (malondialdehyde [MDA], cell membrane permeability) in soybean seedling roots. The 1.5 mg L(-1) BPA exposure did not affect test indices in the roots. Exposure to 3.0 mg L(-1) , 6.0 mg L(-1) , 12.0 mg L(-1) , or 24.0 mg L(-1) BPA caused increases in SOD (except for 3.0 mg L(-1) BPA) and CAT activities, as well as in AsA, proline, and GSH (except for 3.0 mg L(-1) BPA) content, leading to increases in the H2 O2 and O2 (-) content and to membrane lipid peroxidation. Exposure to 48.0 mg L(-1) or 96.0 mg L(-1) BPA caused decreases in the CAT activity and AsA/GSH content, as well as increases in the SOD and POD activities and the proline content, leading to excess ROS accumulation (i.e., H2 O2 and O2 (-) ) and cell membrane damage. After withdrawal of BPA exposure, ROS accumulation and membrane lipid peroxidation were alleviated by regulating a special antioxidant enzyme or substance.