A Review on the Toxicity Mechanisms and Potential Risks of Engineered Nanoparticles to Plants

Studies have reported that typical nanomaterials (NMs) have been applied on a large scale to various human consumer products due to their rapid development. Nanoparticles (NPs) flowing into the environment inevitably exhibit toxicological effects on organisms at the physiological and molecular levels. To identify the mechanisms of phytotoxicity regulation of typical metal-based engineered NPs, a review of ecotoxicological effects and environmental risks of particles is required. The biological transport of NPs in cells frequently affects the physiological state of plants, resulting in growth restriction of seedlings and structural damage to cellular tissues. Subsequently, excessive accumulation of reactive oxygen species (ROS) enhances oxidative stress, metabolic disorders, cell death, and DNA damage. The transcriptome and metabolome of the antioxidant system were also highly activated to resist ROS, which inevitably caused cytotoxicity and dysregulation of metabolic activity. At the biological process, protein folding, imbalance of calcium homeostasis, impaired mitosis, abnormal electron transport in photosynthesis, and dysregulation of TCA cycle in respiration have been extensively explored in the nanotoxicology field. Trophic transfer in the food chain indicates that ingested NPs are highly probable to accumulate in aquatic and terrestrial food chains and eventually pose potential threats to human health. Overall, this review aims to emphasize the toxicological effects of typical NMs on plants, reveal the toxicity mechanisms of plant cells with metal-based NPs in the environment, and discuss potential risks of particles in aquatic and terrestrial food chains, paving a bright path for environmental risk studies of NMs.