In summary, ethylene stimulated respira-tion in carrots and lettuce, isocoumarin accu-mulation in carrots, and RS development in lettuce. The increase in respiration, as well as isocoumarin accumulation and RS develop-ment, was prevented by MCP treatment prior to ethylene exposure. Other reports demon-strated that MCP inhibits ethylene-induced senescence of broccoli (Fan and Mattheis, 2000; Ku and Wills, 1999). The reduction in ethylene action induced by MCP treatment may be a useful means to prevent undesirable ethylene effects during storage of many veg-etables.