Dualistic effects of bisphenol A on growth, photosynthetic and oxidative stress of duckweed (Lemna minor)

In this study, we exposed duckweed (Lemna minor), a floating freshwater plant, to BPA at different concentrations (0, 1, 5, 20, and 50 mg/L) for 7 days so as to investigate the effects of BPA on its growth, photosynthesis, antioxidant system, and osmotic substances. It was found that BPA had the acute toxic effects of low promotion and high inhibition on growth and photosynthesis. Specifically, BPA at a low concentration (5 mg/L) significantly promoted the plant growth and improved the concentration of photosynthetic pigments (chlorophyll a, b, and total Chl ) of L. minor. However, BPA at a high concentration (50 mg/L) significantly inhibited the plant growth, the Chl content, and the maximal photochemical efficiency (F-v/F-m). Furthermore, BPA with high concentration (50 mg/L) induced ROS accumulation and increased the activities of antioxidant enzymes (SOD, CAT, POD, APX, and GR) and the contents of antioxidant substances (GSH, proline, and T-AOC), which indicated that L. minor might tolerate BPA toxicity by activating an antioxidant defense system. The correlation analysis revealed that the fresh weight of L. minor was significantly and positively correlated with photosynthesis and the contents of soluble protein and sugar, while it was negatively correlated with the content of H2O2. Totally, these results showed that BPA at different concentrations had dualistic effects on the growth of L. minor, which was attributed to the alterations of photosynthesis, oxidative stress, and osmotic regulation systems and provided a novel insight for studying the effects of BPA on aquatic plant physiology.

Automated summary

This study investigated the effects of different concentrations of BPA on the growth, photosynthesis, antioxidant system, and osmotic substances of duckweed. The results showed that low concentrations of BPA promoted plant growth and improved the concentration of photosynthetic pigments, while high concentrations of BPA inhibited growth and photosynthesis. Additionally, high concentrations of BPA induced oxidative stress and activated the antioxidant defense system in the plants. These findings provide new insights into the effects of BPA on aquatic plant physiology.