CeO2 Nanozymes as redox regulators: Reprogramming of reactive oxygen species (ROS) signaling for plant climate resilience.

Climate change-induced abiotic stress, including heat, cold, salinity, and drought, increasingly threaten global crop productivity. These challenges highlight the need for complementary strategies alongside conventional genetic improvement. Reactive oxygen species (ROS) act both as cytotoxic molecules causing oxidative damage and as essential signaling regulators controlling redox homeostasis and stress adaptation. This review examines recent advances in engineering nanozymes (NZs) for targeted regulation of plant ROS networks. NZs exhibit dual functions as antioxidant ROS scavengers, and modulators of redox signaling, with nanoceria (CeO2), serving as key example due to its enzyme-mimetic antioxidant activity. Beyond ROS scavenging, emerging evidence suggests that nanoceria can modulate molecular stress signaling pathways, including Ca2⁺ fluxes and phytohormone interactions involving auxin (IAA), abscisic acid, and jasmonic acid. Such ROS reprogramming may trigger hormetic responses that enhance plant tolerance to environmental stress. We further discuss design of smart nanocarriers for targeted and stress-responsive modulation of plant defense pathways. Finally, we highlight future research directions, including experimental standardization and integration of artificial intelligence (AI) and machine learning (ML) to predict NZ-plant interactions based on physicochemical properties. Together, these advances position CeO2 NZs as a promising tool for molecular reprogramming of oxidative homeostasis toward improved climate resilience.