Modified atmosphere packaging delays postharvest leaf senescence of Chinese flowering cabbage via suppressing chloroplast dismantling and alleviating mitochondrial oxidative damage

Abstract

Onset of leaf senescence comes with biomolecule degradation and cellular organelle degeneration. Here, we examined the efficacy of modified atmosphere packaging (MAP) on reactive oxygen species (ROS) metabolism and ultrastructural changes of chloroplasts and mitochondria in Chinese flowering cabbage leaves during storage at 20 ± 1 ℃. MAP delayed chloroplast dismantling along with lower chlorophyll reduction and Fv/Fm ratio. Furthermore, the integrity of mitochondrial ultrastructure was maintained by MAP treatment during leaf senescence. MAP treatment also lowered accumulation of ROS and maintained higher levels of key components and enzyme activity of ascorbate–glutathione cycle, as well as expression of BrAPX5, BrGR, BrDHAR1 and BrMDHAR2. Additionally, MAP-treated cabbage leaves showed higher activity of peroxidase, superoxide dismutase, catalase and encoding gene expressions. Collectively, above findings suggest that MAP treatment could suppress chloroplast dismantling and maintain ROS homeostasis to mitigate mitochondrial oxidative damage and sustain mitochondrial structure, thereby postponing senescence of Chinese flowering cabbage.