Effect of bisphenol A-induced oxidative stress on the ultra structure and antioxidant defence system of Arabidopsis thialiana leaves

Bisphenol A (BPA) is an emerging environmental pollutant with potentially toxic effects on living organisms. The present study was undertaken to analyze the effects of BPA on the leaves of Arabidopsis thialina by determining the levels of photosynthetic pigments, reactive oxygen species (ROS), membrane lipid peroxidation, and ultrastructural malformation. The obtained results revealed that while a low dose of BPA (10μM) did not alter the test indices significantly, it did cause significant changes in all test indices at higher concentrations. Upon exposure to 40 μM BPA, chlorophyll a and chlorophyll b content showed a decrease of 33% and 30%, respectively. It significantly increased ROS contents and lipid peroxidation at 40 μM BPA exposure. Biochemical and gene expression analysis revealed that the antioxidant system was activated and mounted a defense against BPA-induced ROS. In the case of superoxide dismutase (SOD), 40 μM of BPA caused an increase of 151%. However, the malfunctioning of ascorbate peroxidase (APX) and catalase (CAT) at the highest dose of BPA (40 μM) resulted in incomplete activation of the antioxidant defensive system. BPA stress significantly altered the ultrastructure of cells as evidenced by the reduced number of starch grains, damaged chloroplast and mitochondria, and altered leaf epidermal surface, guard cells, and stomata. It is concluded that observed adverse effects in Arabidopsis leaves in response to BPA exposure could be attributed to BPA-induced oxidative stress.