Accumulation of nanoplastics by wheat seedling roots: Both passive and energy-consuming processes

Nanoplastics can transfer from the environment to plants and potentially harm organisms. However, the mechanisms on how crop root systems absorb and transport nanoplastics are still unclear. Here, original and fluorescent labeled polystyrene and polyvinyl chloride nanoparticles (PS-NPs, PVC-NPs; 30 nm; 10 mg L^-1) were employed to study the distribution and internalization pathways in wheat seedling roots. In the study, nanoplastics accumulated more in the root tip and surface, with PVC-NPs more prevalent than PS-NPs. After being treated with inhibitors (Na₃VO₄, chlorpromazine and amiloride), the nanoplastics mean fluorescence intensities were reduced by 4.0-51.1 %. During the uptake, both passive and energy-consuming pathways occurred. For the energy-consuming uptake pathway, macropinocytosis contributed more to cytoplasm than clathrin-mediated endocytosis. H⁺ influx was observed during nanoplastic transport into the cytoplasm, and the reduction in plasma membrane ATPase activity led to a decrease in nanoplastic internalization. These results elucidate the pathways of nanoplastics absorption and transport in wheat roots, provide crucial evidence for assessing nanoplastics' ecological risks and support the development of technologies to block nanoplastics absorption by crop roots, ensuring agricultural and ecosystem safety.