Ce/Mn-MOF with Multiple Enzyme-Mimetic Activities Enables the Alleviation of Plant Saline-Alkali Stress

Abstract Saline-alkali stress impairs plant growth via ROS overaccumulation, while MOF nanozymes offer a promising redox-regulation strategy. In this study, a Ce/Mn-MOF nanozyme was synthesized via a solvothermal method through a bimetallic doping strategy. The reversible valence transitions of bimetallic ions (Ce3+/Ce4+ and Mn2+/Mn3+) promote electron transfer, endowing the Ce/Mn-MOF with superoxide-like (SOD), catalase-like (CAT), and glutathione peroxidase-like (GPx) activities. It exhibits efficient cascade catalytic capability for reactive oxygen species (ROS) scavenging, enabling the conversion of superoxide radicals (O2•−) and hydrogen peroxide (H2O2) into less harmful species. Furthermore, the Ce/Mn-MOF demonstrates low toxicity, ensuring good biocompatibility and safety. It also enhances stress tolerance while promoting biological growth by scavenging excess ROS in plants and thereby alleviating oxidative stress. The Ce/Mn-MOF significantly improved the indicators of mung bean under saline‑alkali stress. Photosynthesis with Pn increased by 93.2%, Gsw by 33.3%, and Tr by 34.0%. It raised SOD activity by 66.84% and CAT activity by 39.97%. Meanwhile, the Ce/Mn-MOF can be used in both hydroponic and soil cultivation systems, further demonstrating the applicability of the Ce/Mn-MOF in agricultural practice. This study provides insights into the application of nanozymes and lays a foundation for promoting the diversified application of nanotechnology in modern agriculture.