Foliar Spray of Cerium Oxide Nanoparticles (CeO2 NPs) Improves Lead (Pb) Resistance in Rice

The widespread use of lead (Pb) has led to serious environmental and human health problems worldwide. The application of oxide nanoparticles (CeO₂ NPs) in alleviating abiotic stress in plants has received extensive attention. In this study, 50 mg·L^-1 CeO₂ NPs can improve Pb resistance and promote rice growth. Specifically, this study observed that CeO₂ NPs increased the activity of antioxidant enzymes peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), but the difference did not reach a significant level. At the same time, CeO₂ NPs upregulated antioxidant metabolites alpha-linolenic acid, linoleic acid, ferulic acid, and kaempferol under Pb stress. In addition, CeO₂ NPs upregulated multiple defense response-related genes, such as <i>OsOPR1</i> and <i>OsPR10a</i>; <i>RPR10a</i>, and improved rice carbon flow and energy supply by upregulating sucrose and D-glucose. The results of this study provided technical support for alleviating Pb stress in rice.