Formation of flavonoids, especially anthocyanin and chlorogenic acid in 'Jonagold' apple skin: Influences of growth regulators and fruit maturity

Abstract

The influences of ethephon, (S)-trans-2-amino-4-(2-aminoethoxy)-3-butenoic acid hydrochloride (ABG-3168), gibberellins (GA4+7 and GA3), alar, cycocel (CCC), prohexadione-Ca, seniphos, shikimic acid, plantacur-E and galactose on the accumulation of flavonoids and chlorogenic acid in 'Jonagold' apple skin were investigated, with emphasis on anthocyanin, in order to separate maturity-related from other development-related influences. Fruit maturation/ripening as determined by both Streif and Starch indices was not affected by these chemicals though applied according to standard procedures. Ethephon application greatly increased anthocyanin accumulation but not that of other flavonoid compounds and chlorogenic acid compared to the control. ABG and GA3 applications significantly retarded anthocyanin accumulation but not that of other flavonoid compounds and chlorogenic acid. ABG delayed the transition to fast anthocyanin accumulation by about 2 weeks compared to the control and other treatments. The application of alar, CCC, prohexadione-Ca, GA4+7, plantacur-E, shikimic acid, galactose and seniphos did not significantly influence the formation of anthocyanin, total flavonoids and chlorogenic acid in fruit skin. The percentage of blush increased during maturation and was higher in ethephon-treated fruit and lower in ABG and GA3-treated fruit compared with the control. The finding that anthocyanin responds much quicker both to ethylene promoting and ethylene inhibiting treatments than other ripening related phenomena suggests that the dependence of anthocyanin synthesis on ethylene is at least complicated. © 2002 Elsevier Science B.V. All rights reserved.