Chlorogenic acid mitigates postharvest broccoli senescence through modulation of oxidative stress and ascorbate-glutathione cycle.

Postharvest broccoli is highly susceptible to water loss and wilting, accompanied by a color deterioration of the heads from dark green to yellow, severely compromising its commercial value. The effects and underlying mechanisms of chlorogenic acid (CGA) treatment on reactive oxygen species (ROS) metabolism and ascorbate-glutathione (AsA-GSH) cycle in broccoli were investigated. The results showed that CGA treatment efficiently mitigated the quality deterioration in broccoli, which was evidenced by the lower yellowing index, the higher h° value and chlorophyll level of the treated samples. This treatment also alleviated oxidative damage by promoting the activities of superoxide dismutase and peroxidase, further preventing the accumulation of lipid peroxidation product malondialdehyde. Higher AsA and GSH contents were observed in treated broccoli, which was associated with the activities of key enzymes in the AsA-GSH cycle, thus enhancing the AsA/dehydroascorbic acid (DHA) and GSH/glutathione disulfide (GSSG) ratios. In addition, the expression of genes encoding antioxidant enzymes (BoSOD and BoPOD) and AsA-GSH cycle key enzymes (BoGR, BoMDHAR, Bo6PGDH and BoGLDH) were induced upon CGA treatment. Furthermore, bioinformatics analysis revealed that CGA application exerts a positive effect on the antioxidant properties of broccoli. These findings provide novel insights into the regulation of oxidative metabolism in broccoli and demonstrate the promising potential of CGA for postharvest preservation of horticultural products.