Characterization of laccase from apple fruit during postharvest storage and its response to diphenylamine and 1-methylcyclopropene treatments

To gain better understanding on laccase in apples and reveal its role in browning color formation during storage, laccases in apples were investigated. The full-length complementary DNAs encoding laccase genes were obtained from different tissues of apple including flowers, calyx, leaves and fruit peel of 'Red Delicious' and 'Cortland'. The apple laccases were compared to those in other plant species and found to have up to 99% homology to Arabidopsis and litchi. qRT-PCR analysis revealed changes in transcript abundance of LAC genes (2, 7, 9, 12, 14, 15 and 16) during storage and in response to DPA and 1-MCP treatments. Enzyme activity of laccase protein in apple peel increased with storage in control fruit, while decreased significantly with DPA or 1-MCP. Changes in phenolic compounds in pericarp tissues decreased generally during storage, but no significant effect of DPA and 1-MCP treatments on the phenolic compounds was found.