Effects of bisphenol A on antioxidation and nitrogen assimilation of maize seedlings roots

Bisphenol A (BPA) is becoming a potential environmental toxicity factor. However, BPA's effect and function mechanism on maize roots remain unknown. Here, we investigated characters of root growth of maize seedlings exposed to BPA for 8 d and without BPA for 3 d, and a series of indicators on reactive oxygen homeostasis and nitrogen assimilation were measured. High-dose BPA(15 and 50 mg·L^-1) suppressed the root growth and caused increased contents of O₂^ˑ-, H₂O₂ and MDA in maize seedling roots. The disturbed ROS homeostasis resulted from the change of antioxidant enzymes, including the increase of APX, GPX, and CAT, and decrease of SOD and POD, and a decrease of antioxidant substance GSH. Meanwhile, High-dose BPA caused a decrease in the soluble protein content, nitrate reductase (NR), glutamate dehydrogenase (GDH), and glutamine oxoglutarate aminotransferase (GOGAT) under the BPA processing phase and recovery period. The low-dose BPA（1.5 and 5 mg·L^-1）significantly promoted root growth of maize seedlings and maintained the ROS homeostasis through antioxidant enzyme APX and GPX eliminating redundant ROS. Our results showed that BPA could cause a dual effect on the root growth of maize seedlings, that is, promotion of low-dose and inhibition of high-dose, through ROS homeostasis and nitrogen assimilation in Zea mays.