ITRAQ-based proteomic analysis reveals that energy waste caused by transmembrane transport disruption accelerated the ripening and senescence of postharvest broccoli heads under high O2 stress

Abstract

Ripening and senescence of horticultural products involve in different metabolic processes, but the understanding of these processes at the proteomics level remains unknown. In this study, a proteomic technique was used for investigating the expression changes of proteins in broccoli heads under 5% O2 + 5% CO2, 20% O2 + 5% CO2 and 40% O2 + 5% CO2 treatments. A total of 54 differentially expressed proteins (fold change ≥1.5) associating with ripening and senescence were identified. The results indicated that high O2 treatment promoted the degradation of carbohydrate, lipid, amino acid and protein, thereby providing more substrates for energy production, in turn, accelerated the biosynthesis of lipid, amino acid, and protein. However, high O2 treatment disrupted vesicle and transmembrane transport and inhibited the transport of these metabolites to specific organelles, thereby resulting in energy waste in postharvest broccoli heads. Therefore, we concluded that energy waste caused by the damage of transmembrane transport might be responsible for broccoli head ripening and senescence under high O2 stress. In summary, this study revealed a comprehensive and interacting metabolic network of postharvest broccoli head ripening and senescence under high O2 stress, which could be used for the development of postharvest preservation technologies to control ripening and senescence of horticultural products.