Up-regulation of Genes in Diphenylamine- and 1-Methylcyclopropene-treated Apples during Cold Storage

Cold storage reduces the rate of quality loss and extends availability of fresh apples in the marketplace, but several  cultivars develop various postharvest browning disorders of the peel or flesh tissue such as superficial scald and external carbon dioxide injury.  Postharvest 1-methylcyclopropene (1-MCP) treatment inhibits ethylene perception and subsequently its production, and as a result inhibits superficial scald development in ‘Granny Smith’.  1-MCP treatment of ‘Empire’, however, can enhance susceptibility of fruit to external carbon dioxide injury. Postharvest drenching with the antioxidant diphenylamine (DPA) reduces or eliminates incidence of both disorders.  Transcriptomic changes using deep sequencing were evaluated during storage of 1-MCP or DPA treated ‘Granny Smith’ and ‘Empire’.  Multivariate analysis was used to find which genes were most associated with 1-MCP treatment during storage.  Multiple genes were upregulated only in 1-MCP treated fruit during storage in both cultivars.  It is suspected that genes associated with greater carbon dioxide injury risk reside within this group.