Treatments that suppress ethylene production or ethylene action modify ADH and AAT gene expression and aroma-related enzyme activities in 'Delbarde Estivale' apple: consequences for the aroma profiles of fruit.

摘要

Effects of aminoethoxyvinylglycine (AVG; ReTainReg.) and 1-methylcyclopropene (1-MCP; SmartFreshReg.) on biosynthesis of aroma volatiles and overall quality of cv. Delbarde Estivale, an early apple variety, were determined. Apples were treated with AVG 3 wk before commercial harvest following standard procedures. 1-MCP was applied directly after harvest. Treated and untreated fruits were kept at room temp. and analysed periodically thereafter. Results indicated that both ethylene-suppressing treatments improved fruit firmness, total acidity and preserved peel colour during shelf life. However, both treatments had a negative impact on biosynthesis of aroma volatiles, a major attribute for sensory quality of apples. Production of straight chain esters was particularly affected. Activities of lipoxygenase (LOX), alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) were reduced by both treatments, in some instances to <50% of that in untreated controls; whereas activity of alcohol o-acyltransferase (AAT) was higher in 1-MCP-treated fruits. Measuring the levels of expression of genes encoding ADH and AAT confirmed results and the importance of an adequate supply of substrates for biosynthesis of volatile esters in apples.