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

1-Methylcyclopropene (1-MCP), a competitive inhibitor of ethylene action, b inds to the ethylene receptor to regulate tissue responses to ethylene. In this work, we investigated the effects of 1-MCP and exogenous ethylene on r ipening, respiration rate, ionic conductivity and peroxidase activity in st rawberry fruit. Strawberry fruit can ripen without exogenous ethylene treat ment, but exogenous ethylene induces secondary ripening processes. Results indicated that stimulation of respiration by ethylene was dose-dependent. F ruit colour development and softening were slightly accelerated by ethylene , but changes in soluble solid content were not. 1-MCP may/may not affect t he respiratory rise induced by exogenous ethylene dependent on fruit maturi ty. Cycloheximide (CHI) reduced the ethylene-induced respiratory increase. Combinations of 1-MCP and CHI reduced respiration more than CHI alone. 1-MC P and CHI did not influence the primary respiratory change in non ethylene- treated fruit. This indicates that ethylene induced respiratory increase ma y involve an ethylene receptor in early harvested fruit, but not in later h arvested fruit. Exogenous ethylene stimulated respiration by regulating new respiratory enzyme(s) synthesis in strawberry fruit. Ethylene induced an i onic leakage increase, and this was positively correlated to fruit water lo ss and peroxidase activity. These results suggest that non-climacteric frui t, such as strawberry, may have different ethylene receptor(s) and/or ethyl ene receptor(s) may have different regulatory functions. It may be the seco ndary effect of ethylene to stimulate respiration in strawberry. Non-climac teric fruit ripening may be related to the development of active oxygen spe cies (AOS) induced by postharvest stress.