Abstract Litchi (Litchi chinensis Sonn.) is a representative non-climacteric fruit species characterized by highly active aerobic respiratory metabolism and rapid progression of senescence during postharvest storage. The efficacy of 1-methylcyclopropene (1-MCP) in delaying senescence and inhibiting pericarp browning of litchi fruit was evaluated during storage at 4 °C. The findings demonstrated that 1-MCP application persistently suppressed the browning index, anthocyanin degradation, and color loss (lightness and hue angle). Additionally, 1-MCP effectively inhibited the production or accumulation of H2O2 and O2−· and lowered relative electric conductivity, malondialdehyde (MDA) content, and protein carbonylation content. The low accumulation of reactive oxygen species (ROS) homeostasis stems from potentiated antioxidant defenses, marked by elevated total flavonoids, phenolics, and ROS-scavenging enzyme activities (catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR)). Moreover, 1-MCP specifically upregulated the oxidative repair gene LcMsrB1 and suppressed key browning enzymes polyphenol oxidase (PPO) and peroxidase (POD). Correlation analysis further confirmed that browning index was positively correlated with ROS, membrane damage, and PPO/POD activity, and negatively correlated with antioxidants, LcMsrB1 expression, GR/SOD activity, and anthocyanin/phenol content. These findings indicate that 1-MCP delays senescence and browning by competitively binding to ethylene receptors to block ripening signals, modulating the expression of REDOX related enzyme genes and ROS metabolism, enhancing antioxidant/repair systems, and preserving membrane/protein integrity.
Cao et al. (Mon,) studied this question.