CeO2-NPs alleviates Cd toxicity in red fescue by enhancing antioxidant defense and metabolic regulation

Cadmium (Cd) contamination in soil severely threatens plant growth and ecological safety. Engineered nanomaterials, as a newly emerging form with characteristics of environmental protection and efficient absorption, have potential in mitigating response of crops to abiotic stresses, while it is only limited understanding role of engineered nanomaterials on alleviating Cd toxicity in plants used for ecological restoration. This study using morpho-physiological and multi-omics methods, it’s found that foliar application of 100-500 mg/L CeO 2 nanoparticles (NPs) significantly promoted plant growth, improved photosynthesis and antioxidant capacity, while reduced Cd uptake and translocation in two red fescue ( Festuca rubra L.) cultivars under Cd stress. Moreover, the concentration of 350 mg/L was most effective. Integrated transcriptomic and metabolomic analyses revealed that CeO 2 -NPs affect the key pathways including ‘flavone and flavonol biosynthesis’ and ‘D-amino acid metabolism’. Further screening revealed that rutin is the key metabolite regulated by CeO 2 -NPs, furthermore, functional verification showed that application of key metabolite rutin enhanced Cd tolerance by inhibiting the formation of hydrogen peroxide and oxygen free radicals, and activating the antioxidant defense system in red fescue. In summary, CeO 2 -NPs alleviates Cd toxicity in red fescue through regulating key metabolic substances to enhance antioxidant capacity and reducing Cd accumulation. This study provides novel insights into the nano-enabled strategy for the phytoremediation and safe utilization of Cd-contaminated soils.