Integrated transcriptomic and metabolomic analysis reveals the effects and potential mechanism of hydrogen peroxide on pigment metabolism in postharvest broccoli

To understand the effects and related potential mechanism of H₂O₂ on pigment metabolism in postharvest broccoli, an integrated analysis of transcriptome and metabolome was performed. Results suggested that 65 differentially expressed genes and 26 differentially accumulated metabolites involved in chlorophyll, carotenoid, and flavonoid metabolism were identified. H₂O₂ treatment delayed the decrease of chlorophyll content by upregulating the expressions of chlorophyll synthetic genes, thylakoid synthetic genes, and 15 light-harvesting complex genes compared with the control and diphenylene iodonium treatments. H₂O₂ treatment decreased the accumulation of 11 flavonoids and 5 flavonols by downregulating the flavonoid synthetic genes. In addition, H₂O₂ treatment promoted carotenoid biosynthesis to eliminate reactive oxygen species in thylakoids, thereby protecting chlorophyll molecules from degradation. The inhibition of flavonoids and flavonols accumulation and chlorophyll decrease was the crucial reason for the delayed yellowing in H₂O₂ treatment. This study provides a new method and theoretical support for delaying the yellowing process in postharvest broccoli.