Melatonin alleviates cadmium toxicity in Solanum nigrum by enhancing pectin-mediated cell wall sequestration and antioxidant

Abstract

, whereas melatonin partially restored these traits. Melatonin also decreased Cd concentrations in roots, stems, and leaves and reduced root-to-shoot Cd translocation. Meanwhile, Cd partitioning to the cell-wall fraction increased from 56.7% to 67.5% in roots and from 55.1% to 66.5% in leaves, while organellar Cd partitioning was approximately halved. These changes were accompanied by increased pectin content and pectin-bound Cd, upregulation of pectin metabolism and Cd detoxification genes, enhanced antioxidant activity, and improved redox status. Random forest modeling identified ascorbate, photosynthetic rate, and pectin-bound Cd as key predictors of Cd tolerance. These findings indicate that melatonin enhances Cd tolerance through coordinated cell-wall sequestration and antioxidant defense while altering Cd allocation, with implications for phytoremediation efficiency.