Multi‐Scale Mechanisms of Zn‐Se Antagonism in Wheat After Spray: From Subcellular Sequestration to Transcriptional Regulation

Foliar Zn‐Se application is a promising strategy to alleviate human micronutrient deficiencies, yet their interaction during co‐application remains unclear. Through field and pot experiments, we investigated Zn‐Se antagonism in wheat across organ allocation, subcellular distribution, and transcriptomic regulation. Co‐application decreased grain Se concentration while increasing Se allocation to leaves and reversed the positive correlation between grain Se and leaf‐to‐sheath translocation factor. Zn enhanced Se sequestration in leaf cell walls and soluble fractions. Transcriptomic analysis revealed that altered expression of key genes in related metabolic pathways, including SULTR3;4 and PHT2 , leads to Se compartmentalization in leaves and restricts Se transfer to grains and accumulation. Despite antagonism, co‐application produced grains meeting Zn and Se Recommended Nutrient Intake, enhanced antioxidant capacity, and posed low ecological risk upon straw return. These results elucidate a mechanistic framework for Zn inhibiting Se remobilization to grains and provide molecular targets for optimizing Zn‐Se co‐biofortification in wheat.