Depression of Autocatalytic Ethylene Production by High-temperature Treatment in Carnation Flowers

In carnation flowers, high temperatures have been shown to inhibit the induction of autocatalytic ethylene production and petal wilting. In this study, we investigated the effect of high temperature on ethylene production and petal wilting in carnation flowers after initiation of autocatalytic ethylene production. Transferring carnation flowers to high-temperature conditions (38 degrees C) following the initiation of ethylene production by exposure to exogenous ethylene suppressed the autocatalytic increase in ethylene production. High-temperature treatment also depressed ethylene production in carnation flowers producing high levels of ethylene. In petals of these flowers held at 38 degrees C, 1-aminocyclopropane-1-carboxylate synthase (ACS) and 1-aminocyclopropane-1-carboxylate oxidase (ACO) activities were depressed with greater depression in ACS activity; however, the progression of petal wilting was not suppressed in high-temperature-treated flowers. These results indicate that high temperature depresses ethylene production but has little effect on petal wilting in carnation flowers once ethylene production has been initiated.