External Sucrose Delays Pakchoi Senescence Through Regulating Energy Metabolism

As a typical green leafy vegetable, pakchoi suffers greatly from postharvest loss. This study investigated the impact of sucrose on quality and energy metabolism of postharvest pakchoi. Sucrose could delay leaf yellowing and preserve higher chlorophyll and decrease weight loss rate and respiration rate during pakchoi storage. Compared with control, the sucrose-treated group retained higher energy level as indicated by higher contents of adenosine triphosphate (ATP) and adenosine diphosphate (ADP), as well as higher activities of cytochrome c oxidase (CCO), succinic dehydrogenase (SDH), and adenosine triphosphatase (ATPase). Moreover, sucrose could induce the expression of BrATP4, BrAtpB, BrSDH1, and BrCOX5/6, while BrSDH6 was repressed. Correlation analysis results presented that ATP was significantly positively correlated with ADP, energy charge (EC), and H⁺K⁺-ATPase, and CCO presented positive correlation with BrCOX5/6. Higher chlorophyll was related to higher energy status of postharvest pakchoi. Above findings demonstrated that sucrose might delay pakchoi senescence and yellowing by maintaining higher energy, energy metabolism–related enzyme activities, and gene expression levels.