Comparative Physiological and Transcriptomic Analyses Reveal Enhanced Mitigation of Cadmium Stress in Peanut by Combined Fe3O4/ZnO Nanoparticles

Abstract

Cadmium (Cd) pollution poses a significant threat to food safety and human health. Foliar spraying of nanomaterials has been widely used to mitigate Cd stress in agriculture. However, the effects and synergistic mechanisms of various nanomaterial combinations on Cd resistance remain unclear. This study compared the impacts of Fe₃O₄ nanoparticles (NPs), ZnO NPs, and their combinations at different concentrations (50-400 mg/L) on the growth and physiology of peanuts under Cd-stress. Results showed that combined-NPs reduced Cd accumulation and enhanced plant growth more effectively than single-NPs. Specifically, the concentrations of Cd in roots and shoots were reduced by 52.13% and 47.83%, respectively, while biomass increased by 42.86% for roots and 100.17% for shoots. A concentration of 150 mg/L of combined NPs was optimal, reducing root Cd concentration from 0.619 mg/g to 0.245 mg/g and shoot from 0.187 mg/g to 0.148 mg/g. Transcriptomic analysis revealed that combined NPs upregulated oxidative stress-related genes (GST23, POD2) to strengthen antioxidant defenses. Simultaneously, they also downregulated metal transports (ABCC2, Nramp2, ABCG29, ABCG2), potentially limiting Cd uptake. These findings reveal the synergistic mechanism of enhancing antioxidant systems and regulating metal transport pathways, offering a new strategy to develop combined nano-fertilizers that combat Cd pollution in similar crops.