Maize root exudates modulate laccase-catalyzed polymerization of endocrine-disrupting chemicals to mitigate crop...

Laccase catalysis represents a promising green strategy for mitigating endocrine-disrupting chemicals (EDCs) and sequestering organic carbon in agroecosystems. However, the mechanistic role of root-exuded metabolites in modulating laccase-catalyzed EDC rhizoremediation within maize (Zea mays L.) systems remains poorly understood. Here, we probed the influence of maize root exudates (M-REs) on laccase-catalyzed EDC single-electron oxidation and subsequent contaminant uptake at environmentally relevant concentrations. Relative to control treatments without M-REs, supplementation with 10-80 mg L^-1 M-REs suppressed laccase-catalyzed bisphenol A transformation, whereas 5-10 mg L^-1 M-REs enhanced the transformation of 17β-estradiol. Covalent co-dimers were identified as reaction products between EDCs and key constituents of M-REs, including phenolic acids (vanillic acid, ferulic acid, protocatechuic acid) and amino acids (glutamic acid, phenylalanine). Notably, prolonged laccase-catalyzed polymerization led to the formation of highly complex, insoluble co-polymers via cross-linking of EDCs with exudate components. These precipitated polymers exhibited low bioavailability and minimal mobility, resulting in significantly reduced EDC phytotoxicity, as evidenced by an improved germination index. Pot trials further demonstrated that laccase-regulated rhizoremediation decreased root uptake rate constants by 51.72% for E2 and 20.59% for BPA compared to enzyme-deficient controls. This efficient sequestration markedly limited the translocation of EDCs to aboveground tissues, thereby minimizing their potential entry into the food chain. Collectively, these findings elucidate the mechanistic role of M-REs in modulating laccase-catalyzed EDC polymerization and subsequent uptake, thereby advancing the development of sustainable and eco-friendly rhizoremediation strategies to support safe agricultural production.