Environmental levels of indole-3-acetic acid enhance the uptake and translocation of polyfluoroalkyl ether sulfonates in wheat

As a group of concerned organic pollutants, polyfluoroalkyl substances (PFAS) are able to accumulate in crops, thereby posing potential ecological risks. Phytohormone herbicides, such as indole-3-acetic acid (IAA), are widely used in agriculture to control weeds. Here, we found that IAA at environmentally relevant concentrations promoted the absorption and translocation of 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA) in wheat via activated multiple channel proteins. Furthermore, IAA facilitated unloading of 6:2 Cl-PFESA from cortex to xylem, thereby significantly promoting its translocation. The conformation transformation of channel proteins regulated by IAA greatly promotes dissociation of 6:2 Cl-PFESA from the bound proteins. The electrostatic interaction between 6:2 Cl-PFESA and gate residues enlarges the channel radius and promotes its absorption. These findings provide the evidence regarding the potential ecological risks associated with 6:2 Cl-PFESA accumulation in wheat caused by the application of IAA in agriculture. Commonly used auxin herbicides at environmentally relevant concentrations promoted the absorption and translocation of chlorinated polyfluoroalkyl sulfonate in wheat, indicating ecological risk, according to plant exposure experiments.