Synergistic Uptake of Nanoplastics and Sodium Chloride in Tall Fescue Roots Mediated by Cell Wall Architecture

Strategic application of irrigation, mulching, and sludge enhances crop yields in saline-alkali soils; however, leading to micro/nanoplastics (M/NPs) accumulating in the soil, posing threats to plant growth and environmental safety. This study explored the combined effects of polystyrene (PS)-NPs and salt stress on tall fescue (<i>Festuca arundinacea</i>). Results indicated that compared to exposure to NPs or NaCl individually, the combined stress significantly enhanced the uptake and accumulation of NPs and NaCl in plant tissues, leading to reducing shoot length by 93.3%, root length by 79.1%, and chlorophyll content by 55.7%. These synergistic effects originated from charge-mediated interactions between NPs and Na⁺ ions. Furthermore, NPs altered expression of genes related to cell wall structure, oxidative stress, and membrane permeability, thereby compromising cell wall integrity and reducing the salt tolerance of tall fescue. This research elucidated physiological and biochemical mechanisms through which NPs exacerbate salt stress, highlighting their environmental risks in saline-alkali soil.