Uptake, accumulation, and translocation mechanisms of steroid estrogens in plants

Applying sewage sludge or animal manure onto agricultural land can result in estrogen pollution, which increases the risk of human exposure to steroid estrogens (SEs) via the food chain. However, the uptake and accumulation mechanism of SEs by plants is still unclear. In this study, the uptake, accumulation, and translocation of 17 beta-E2, a representative SE, were investigated through a series of wheat hydroponic experiments. Various inhibitors were applied to explore the uptake pathways of 17 beta-E2 by wheat. In addition, the effects of exposure concentrations, coexisting 17 alpha-ethynylestradiol (EE2) and plant properties on the uptake of 17 beta-E2 were examined. The results indicated that the accumulation of 17 beta-E2 in wheat roots mainly resulted from adsorption and active uptake that involved aquaporins and anion channels transport The chlorophyll and protein contents of plants were positively correlated with the uptake of 17 beta-E2, whereas competitive inhibition occurred when 17 beta-E2 and EE2 coexisted in the same solution. Nevertheless, the results of a split-root experiment showed that 17 beta-E2 absorbed by wheat could further migrate in plant via long-distance transport and ultimately was discharged from plants, suggesting that 17 beta-E2 was still at risk of being released even though it had been absorbed by plants. These results could provide valuable insights into the risk assessment and risk control of the uptake of SEs by plants. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the uptake, accumulation, and translocation mechanisms of 17 beta-E2 in wheat plants, revealing the pathways and factors influencing the uptake of SEs by plants. The results indicated that both adsorption and active uptake were involved in the accumulation of 17 beta-E2 in wheat roots, with chlorophyll and protein contents positively correlated with uptake. Additionally, competitive inhibition was observed when 17 beta-E2 and EE2 coexisted, suggesting a potential risk of SE release even after plant absorption.