Preharvest and postharvest ectoine treatments delay postharvest senescence and yellowing in broccoli

• Ectoine delays postharvest senescence and yellowing of broccoli. • Ectoine mitigates oxidative damage cause by ROS accumulation. • Ectoine promotes flavonoid and glucosinolate biosynthesis in broccoli. • Ectoine modifies the biosynthesis and degradation of chlorophyll in broccoli. • Preharvest application of ectoine most effectively extends the shelf life of broccoli. Ectoine stabilizes the natural configuration of proteins, membranes, and nucleic acids without interfering with the cellular macromolecules. The impact of preharvest or postharvest ectoine treatment on broccoli was investigated, when it stored for 4 d at 20 °C and 90% relative humidity. Results indicated that both preharvest and postharvest ectoine treatments delayed the broccoli senescence by increasing antioxidant enzyme activity and mitigating ROS accumulation. The yellowing index of broccoli in preharvest and postharvest ectoine treatment groups were both < 5 at 4 d of storage and had kept their economic value. Transcriptomic and metabolomic analyses revealed that ectoine treatments modulated the genes expression and metabolites abundance associated with flavonoid biosynthesis and chlorophyll metabolism. The preharvest ectoine treatment downregulated the genes expression ( SGR and NYC1 ) that function in the chlorophyll degradation pathway to greater extent than the postharvest treatment. The chlorophyll content in preharvest treatment groups maintained the highest levels (0.13 g kg −1 ) at end of storage. Broccoli subjected to the preharvest treatment accumulated greater amount of metabolites associated with glucosinolate biosynthesis. These findings indicate that the preharvest spray of ectoine was more effective and convenient than the postharvest treatment in delaying the broccoli yellowing during postharvest storage.