Reactive oxygen species initiate a protective response in plant roots to stress induced by environmental bisphenol A

Bisphenol A (BPA), a contaminant of emerging concern, can affect plant growth and development at high concentrations. Reactive oxygen species (ROS) production is a general primary response in plants to stress. Here, the aim is to investigate whether ROS in plants play protective roles for stress induced by BPA exposure at environmental concentrations. In this study, soybean roots (seedling, flowering and podding stages) were exposed to 1.5 and 3.0 mg L^-1 BPA, and ROS response was measured. The relationship between ROS levels and residual BPA content in soybean roots was evaluated. The results showed that exposure (9 h) to 1.5 mg L^-1 BPA elicited changes in ROS production. ROS then gradually accumulated in soybean roots (seedling stage). Exposure to 3.0 mg L^-1 BPA elicited a stronger and earlier ROS responses at the flowering and podding stage, but did not lead to membrane lipid peroxidation. Residual BPA content in soybean roots reached peak concentrations after 9 h of exposure, and then gradually decreased at the flowering and podding stage. These results indicate that ROS in soybean roots might be involved in the oxidative metabolism of BPA, which could prevent BPA from damaging exposed plants. In conclusion, the observed ROS metabolic effects may be self-protection responses of plants to stress induced by BPA exposure.