Ecological risks of microplastics in soils of major Angelica sinensis production areas and biological responses of...

Farmland microplastic pollution has become an emerging environmental issue in agricultural ecosystems; however, systematic studies on soil microplastic contamination in the main production areas of Angelica sinensis in China and its potential effects on medicinal roots remain limited. This study analyzed the composition, ecological risks, and accumulation and biological effects of microplastics in A. sinensis roots through field investigation combined with controlled experiments. The results indicate that farmland soils in the main production areas of Gansu Province contain relatively high levels of microplastics, posing potential ecological risks. Residual agricultural plastic films and external microplastic inputs significantly increased the exposure and accumulation of microplastics in A. sinensis roots. After accumulating in the roots, polyethylene microplastics (PE-MPs) significantly affected physiological indicators and disturbed the cell wall-plasma membrane interface. Changes in cell wall integrity were perceived by receptors such as Malectin receptors and wall-associated kinases, triggering signal amplification centered on reactive oxygen species (ROS) accumulation and the MAPK cascade, and further coupling with plant hormone and immunity-related pathways to drive root defense and structural adaptation. PE-MPs also induced dose-dependent metabolic reprogramming in mature roots, shifting metabolism from a growth-oriented mode to a stress-adaptive strategy centered on carbon skeleton conservation and metabolic homeostasis. This study reveals a continuous response process from environmental exposure to cellular perception, signal transduction, and metabolic reprogramming under microplastic pollution, providing scientific evidence for soil microplastic risk assessment and quality safety in medicinal plant production areas.