2,4-Epibrassinolide enhances chilling tolerance in postharvest peach fruit through regulation of antioxidant defense, membrane stability, and cell wall metabolism

Peaches are particularly vulnerable to developing chilling injury (CI). Although 2,4-epibrassinolide (EBR) has been reported to alleviate CI, its role in regulating cell wall polysaccharide metabolism remains poorly understood. In this study, a 10 min dip in 5 μmol L⁻¹ EBR delayed CI onset and reduced the final CI index by 50% compared with water-treated controls, while maintaining higher firmness and lower malondialdehyde accumulation. These protective effects were associated with modulated cell wall metabolism. EBR slowed pectin solubilization, with water-soluble pectin 33% lower at 35 d, and suppressed cellulose depolymerization The treatment also reduced the activities of cellulase, polygalacturonase (PG), and pectin methylesterase (PME). Gene expression analysis also suggested lower transcript levels of PpPG, PpPME , and PpXTH1 . Overall, EBR enhances peach chilling tolerance through physiological associations with cell wall polysaccharide stabilization, offering a practical strategy for commercial postharvest management of refrigerated stone fruits.