Comparative transcriptomic analysis reveals the reactive oxygen species metabolism involving in melatonin-alleviated chilling injury in postharvest banana fruit

Banana fruit is susceptible to chilling injury (CI) during cold storage, which causes quality deterioration and commodity value decline. Here, the effects of melatonin on CI alleviation and reactive oxygen species (ROS) metabolism in postharvest banana were studied. The results displayed that 500 mu mol L-1 melatonin treatment effectively inhibited CI development in cold-stored banana during the 96 h of storage. Additionally, lower O2.productive rate and H2O2 content, but higher contents of ascorbic acid (AsA) and glutathione (GSH) were found in melatonin-treated banana, compared with control fruits. Also, melatonin inhibited the declined activities of antioxidant enzymes. Moreover, a total of 1858 and 330 differentially expressed genes (DEGs) were identified between the comparison of CK48h (control bananas at 48 h) and MT48h (melatonin-treated bananas at 48 h), and CK96h (control bananas at 96 h) and MT96h (melatonin-treated bananas at 96 h) through comparative transcriptome analysis of banana fruit, respectively. Further KEGG displayed that DEGs were enriched in secondary metabolites biosynthesis, MAPK signaling pathway-plant and plant hormone signal transduction. The transcriptome expression profiling and RT-qPCR exhibited melatonin treatment improved the expressions of antioxidant enzyme genes (MaSOD, MaCAT, MaAPX and MaGR) but inhibited the expression of ROS production gene (MaRBOH). Collectively, these findings provide a comprehensive view of ROS metabolism associated with the melatonin-alleviated CI in cold-stored banana fruit.