Postharvest senescence profiling in broccoli using Tandem Mass Tagbased proteomics

Abstract

Harvesting fresh produce induces countless changes in different metabolic processes, initiating senescence of the plant tissue. Understanding the changes in protein expression and activity during postharvest senescence can help identify the networks that contribute to quality loss and shelf-life reduction in produce. Identifying these proteins can lead to strategies for extending fruits' and vegetables' freshness and shelf life. In this study, we investigated the proteome-level changes in harvested broccoli florets stored at either room temperature (25 °C) or in refrigerated conditions (4 °C) using Tandem Mass Tag technology (TMT). A lower storage temperature reduced the levels of proteins involved in ubiquitindependent and ubiquitin-independent protein degradation pathways mediated by the 20S and 26S proteasomes and in the RNA-Induced Silencing Complex (RISC) associated with the small interfering RNA (siRNA) pathway. Moreover, we identified protein kinases, transcription factors, and dehydration-related proteins, as well as mapped chemical interaction networks and key pathways active during broccoli senescence. Pathways related to autophagy, ribosome biosynthesis, and carbon metabolism were significantly downregulated under cold temperatures. Proteins related to chlorophyll and reactive oxygen species (ROS) pathways were differentially expressed in harvested broccoli stored at room temperature. The current report facilitates a comprehensive understanding of the complex regulatory orchestration that builds a protein network that could be used for future endeavors in improving the postharvest shelf life of broccoli.