Transcriptomic analysis reveals key genes related to antioxidant mechanisms of Hylocereus undatus quality improvement by trypsin during storage

It has been revealed in our previous studies that trypsin scavenges superoxide anions. In the current study, the mechanisms of storage quality improvement by trypsin were evaluated in H. undatus. Strikingly, the improvement is due not to its antibacterial or antifungal activity but to its superoxide scavenging activity. Moreover, trypsin significantly decreased the levels of ROS, cell permeability and membrane lipid peroxidation. The activities of major antioxidant enzymes were significantly improved by trypsin treatment. Transcriptome profiles of H. undatus treated with trypsin revealed the pathways and regulatory mechanisms of antioxidant genes up or down-regulated following trypsin treatment by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses. The results of protein–protein interaction networks indicated that CAT is the key among the enzymes of the complicated antioxidant system. In addition, the current results showed that the synergistic effect of trypsin with antioxidant enzymes can regulate the levels of endogenous active oxygen species, reduce malondialdehyde content, improve cell membrane integrity, alleviate cell damage and delay fruit ageing.