| Abstract
| - To understand the role of ethylene in regulating the overall flavor of apple fruits, ethylene productionor action was reduced using transgenic apple trees suppressed for ACC-synthase or ACC-oxidaseenzyme activity or by the addition of 1-methylcyclopropene (1-MCP), an ethylene action inhibitor.Flavor components were differentially regulated in response to the suppression of both ethylenebiosynthesis and action. Headspace analysis of aroma production, an ethylene-associated event,showed a reduction in ester and alcohol production in the ethylene-suppressed lines and in the applestreated with 1 μL L-1 1-MCP for 20 h at 20 °C. However, no major differences were observed in theconcentrations of aldehyde volatiles. Other flavor metabolites that showed an ethylene-dependentpattern were organic acids and sugars. Malic acid degradation was significantly reduced underethylene-suppressed conditions, showing a recovery after the fruit was exposed to ethylene. Sucroseand fructose concentrations were influenced by suppression or enhancement of ethylene. Totalphenolics as well as individual phenolic compounds showed an ethylene-dependent regulation onlyin response to the suppression of ethylene biosynthesis, but not when ethylene action was inhibited. Keywords: Aroma; fruit flavor complex; phenolic compounds; sugars; Malus domestica; organic acids;transgenic apple fruit
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