Response of soybean (Glycine max L.) seedlings to polystyrene nanoplastics: Physiological, biochemical, and molecular perspectives.

Micro and nanoplastics are new generation contaminants of global concern. It is important to evaluate the effects on edible products due to the presence of micro- and nano-sized plastics in the treated wastewater. A hydroponic experiment was carried out to explore the effect of polsytrene nanoplastics (PS-NPs; 20 nm) at different concentrations (0, 12.5, 25, and 50 mg L) on Glycine max L. (soybean) seedlings for 7-days. In the current study, firstly the uptake of PS-NPs by Glycine max L. (soybean) roots were confirmed by laser confocal scanning microscope. Exposure to PS-NPs, negatively affected growth parameters and increased Fe, Zn and Mn contents in roots and leaves of soybean seedlings. PS-NPs treatments caused oxidative stress in soybean seedlings. The hydrogen peroxide and malondialdehyde contents, showed similar increase pattern in seedlings exposed to PS-NPs. Response to PS-NPs, the level of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase) and proline content were generally enhanced in roots and leaves of soybean. The expression level of stress-related genes examined in the study included CSD5, FSD3, APX1, and POD up-regulated in PS-NPs treated-soybean seedlings in a tissue specific manner. The results of the present study showed the adverse effects of PS-NPs on soybean seedlings, which may have important implications for the risk assessment of NPs on crop production and environmental safety.