Adaptive strategies of emergent plants to per- and polyfluoroalkyl substances

Emergent macrophytes are key components in the phytoremediation of per- and polyfluoroalkyl substances (PFAS)-contaminated wastewaters, yet comparative evidence on species-specific bioaccumulation and metabolic strategies remains scarce. Here, four typical emergent plants (Juncus effusus (Je), Cyperus alternifolius (Ca), Canna indica (Ci), and Iris tectorum Maxim. (It)) were chosen for PFAS hydroponic experiments. Among the four species, Ca exhibited the highest PFAS concentrations in both roots and shoots (19909.41 ± 45.76 ng/g and 11561.24 ± 97.78 ng/g), correlated with its highest total root length (750.49 cm) and stele area proportion (A_stele/A_root = 0.081). As for novel alternatives, F-53B showed the strongest enrichment and the lower translocation factor (TF < 0.5). Subcellular analyses indicated that short-chain PFAS were mainly distributed in soluble fractions, whereas long-chain PFAS were preferentially retained in cell walls and organelles. The four species developed distinct physiological and metabolic adaptation strategies: In Ca, glutamine/asparagine metabolism was increased to support nitrogen balance, accompanied by increased root activity and pigment contents. Je was characterized mainly by osmotic adjustment and sugar-acid metabolic remodeling. It depended largely on glutathione (GSH)-linked antioxidant and phenylpropanoid defenses, whereas Ci exhibited suppressed nitrogen assimilation and weak antioxidant compensation. These findings reveal species-specific patterns of PFAS accumulation and adaptive responses in emergent macrophytes, providing a scientific basis for plant selection and the optimization of phytoremediation strategies in PFAS-contaminated aquatic systems.