Given the results presented herein, we conclude that 1-MCP
treatment is effective in maintaining acidity and malate content of
harvested apple fruit during storage periods. The mode of action of
1-MCP regulating organic acid metabolism in apple fruit could be
the increased malate biosynthesis via up-regulating MdPEPC and
MdcyMDH expression with higher activity of PEPC and cyNADMDH,
and the decreased malate degradation via limiting MdPEPCK
expression with lower activity of PEPCK. Moreover, 1-MCP
treatment up-regulates acid transport genes, including
MdVHA-A, MdVHP and Ma1, resulting in higher malate contenin the vacuole. Our results provide novel evidence for understanding
molecular mechanism by which 1-MCP regulates organic acid
metabolism in apple fruit during storage periods.