Glycine betaine-modified CeOx/Mn3O4 nanozymes alleviate salt stress in corn by enhancing antioxidant defense

Salt stress triggers excessive reactive oxygen species (ROS) accumulation in plants, causing severe oxidative damage. Developing efficient ROS-scavenging strategies is therefore crucial for enhancing crop salt tolerance. In this study, a glycine betaine (GB)-modified CeOx/Mn3O4 nanozymes system was synthesized to alleviate oxidative stress in corn (Zea mays L.) under salt stress. This material significantly enhances catalase (CAT) and superoxide dismutase (SOD) mimicking activities via interfacial electron transfer, enabling efficient scavenging of superoxide anions (O2•-) and hydrogen peroxide (H2O2). The GB coating improves biocompatibility and contributes to osmotic regulation. Hydroponic screening identified 60 μg mL-1 as the optimal concentration. Under soil culture, nanozyme treatment significantly promoted corn growth compared to salt-stressed controls, increasing fresh weight, dry weight, net photosynthetic rate, transpiration rate, and stomatal conductance by 60.4%, 55.6%, 106.5%, 103.7%, and 104.7%, respectively. Chlorophyll a, chlorophyll b, and total chlorophyll were restored by 36.4%, 42.9%, and 38.5%, while SOD and CAT activities increased by 66.4% and 71.9%, indicating enhanced antioxidant defense. Collectively, CeOx/Mn3O4-GB NPs alleviate oxidative stress and improve photosynthesis, offering a promising nanozyme-based strategy for saline agriculture.