Initiation of ripening capacity in 1-MCP treated green and red ‘Anjou’ pears and associated expression of genes related to ethylene biosynthesis and perception following cold storage and post-storage ethylene conditioning

• Ethylene triggered ripening capacity in 1-MCP treated red ‘Anjou’ after 6 months.
• Ethylene could not trigger ripening capacity in 1-MCP treated green ‘Anjou’.
• Ethylene enhanced ethylene synthesis in 1-MCP treated red but not green ‘Anjou’.
• Ethylene up-regulated PcACO1 in 1-MCP treated red but not green ‘Anjou’.

1-Methylcyclopropene (1-MCP) is valuable technology for control superficial scald (SS) and to extend storage life of European pears, but initiating ripening capacity (RC) of the 1-MCP treated fruit following cold storage is a challenge. Green ‘Anjou’ and its bud mutation red ‘Anjou’ pears at commercial maturity were treated with 1-MCP at 0.15 μL L−1 and stored at −1 °C for 7 months. While control fruit of both cultivars developed RC and SS, 1-MCP treated green and red pears developed neither RC nor SS in 7 d at 20 °C following 2–7 months of storage. RC development was triggered by post-storage ethylene conditioning (PSEC) in 1-MCP treated red but not green pears following 6–7 months of storage. Ethylene production increased in control fruit and was inhibited by 1-MCP in both green and red pears during storage, however, the 1-MCP treated red but not green pears increased ethylene production after 5 months of storage. PSEC enhanced the ethylene production in 1-MCP treated red but not green pears following 6–7 months of storage. In correspondence, the expression of ethylene synthesis genes (PcACO1, PcACS1, PcACS2, PcACS4, and PcACS5) increased after 6 month of storage in 1-MCP treated red but not green pears. The signal genes (PcETR1, PcETR2, PcETR5 and PcCTR1) were stable at extremely low level in 1-MCP treated green and red pears during cold storage. PSEC up-regulated PcACO1 and PcETR2 after 6 months of storage, and down-regulated the other genes in 1-MCP treated red pears, while it down-regulated all the genes in 1-MCP treated green pears. In conclusion, PcACO1 may play an important role in initiating ripening capacity in 1-MCP treated red ‘Anjou’ pear upon PSEC.