Responses of strawberry fruit to 1-Methylcyclopropene (1-MCP) and ethylene

1-Methylcyclopropene (1-MCP), a competitive inhibitor of ethylene action, binds to the ethylene receptor to regulate tissue responses to ethylene. In this work, we investigated the effects of 1-MCP and exogenous ethylene on ripening, respiration rate, ionic conductivity and peroxidase activity in strawberry fruit. Strawberry fruit can ripen without exogenous ethylene treatment, but exogenous ethylene induces secondary ripening processes. Results indicated that stimulation of respiration by ethylene was dose-dependent. Fruit colour development and softening were slightly accelerated by ethylene, but changes in soluble solid content were not. 1-MCP may/may not affect the respiratory rise induced by exogenous ethylene dependent on fruit maturity. Cycloheximide (CHI) reduced the ethylene-induced respiratory increase. Combinations of 1-MCP and CHI reduced respiration more than CHI alone. 1-MCP and CHI did not influence the primary respiratory change in non ethylene-treated fruit. This indicates that ethylene induced respiratory increase may involve an ethylene receptor in early harvested fruit, but not in later harvested fruit. Exogenous ethylene stimulated respiration by regulating new respiratory enzyme(s) synthesis in strawberry fruit. Ethylene induced an ionic leakage increase, and this was positively correlated to fruit water loss and peroxidase activity. These results suggest that non-climacteric fruit, such as strawberry, may have different ethylene receptor(s) and/or ethylene receptor(s) may have different regulatory functions. It may be the secondary effect of ethylene to stimulate respiration in strawberry. Non-climacteric fruit ripening may be related to the development of active oxygen species (AOS) induced by postharvest stress.