Metabolomic and transcriptomic investigations reveal the responses of cucumber leaves exposed to polystyrene nanoplastics (PSNPs)

The uptake and accumulation of nanoplastics by plants have raised particular concerns. However, molecular mechanisms underlying nanoplastic phytotoxicity are still vague and insufficient. Thus, its potential environmental risks and biosafety are receiving increased attention. In this study, cucumber plants were exposed to polystyrene nanoplastics (PSNPs) under different concentration. The results demonstrated that phenotypic parameters (total photosynthetic pigment content, relative membrane permeability, total phenolic content, and lipid peroxidation) were not significantly affected. However, metabolomic and transcriptomic analysis revealed that both doses of PSNPs induced the expression regulation of different key genes, exhibiting considerable distinction on metabolic responses in cucumber. The high dose of PSNPs induced stronger alteration in cucumber leaves than low dose of PSNPs. Low dose exposure significantly affected four metabolic pathways involved in the carbohydrate metabolism. High dose exposure significantly affected five metabolic pathways involved in the carbohydrate metabolism and four metabolic pathways involved in the amino acid metabolism. These findings shed new light on the phytotoxic mechanism and environmental implication behind the interaction of nanoplastics and plants, and advance our understanding of the potential adverse effect induced by the presence of nanoplastics in agricultural systems.