Root Cell Wall Polysaccharides as Key Mediators of Hydrophobic Organic Contaminant Bioaccumulation in Crops

Abstract This study identifies correlative associations pointing to a putative polysaccharide-linked pathway for hydrophobic organic chemical (HOC) bioaccumulation in crops, challenging the conventional lipid-centric model. Our integrated FTIR, NMR, and immunofluorescence data establish links among root cell wall (RCW) polysaccharide profiles, enzyme activities, and differential di-n-butyl phthalate (DBP) sorption and partitioning. Comparing two Brassica parachinensis varieties with divergent DBP accumulation phenotypes, we find that RCW pectin and hemicellulose likely modulate DBP bioaccumulation via shifts in the cell-wall polarity. Under DBP stress, the high-accumulation variety shows elevated pectin/hemicellulose biosynthesis and pectin methyl ester/xyloglucan endotransglucosylase-driven wall remodeling, increasing the wall polarity to weaken root DBP retention and facilitate shoot translocation. The low-accumulation variety exhibits higher pectin methylesterification and attenuated polysaccharide induction, sequestering more DBPs in roots. These results suggest that cell-wall polysaccharides are candidate HOC bioaccumulation regulators, providing potential targets for breeding low-contaminant crop varieties and expanding predictive frameworks for crop safety beyond lipid-based models.