Regulation of Anthocyanin Synthesis in Apple Skin. I. Comparison of the Effects of Cycloheximide, Ultraviolet Light, Wounding and Maturity

Abstract

Cycloheximide applied to apple skin discs inhibited anthocyanin synthesis even at very low concentrations (0.01 �g ml-1) but stimulated accumulation in whole apple skin at concentrations between 0.05 and 30 �g ml-1. When cycloheximide was applied as a drop to whole fruit, anthocyanin synthesis was inhibited in the zone of application. A region of enhanced synthesis surrounded the inhibited area when the concentration was 1 �g ml-1 or higher. Inhibition appears to be the primary effect, while stimulation is a secondary effect of the application of cycloheximide. Similarly, exposure to u.v. light for 5-60 min promoted anthocyanin accumulation. Wounding of fruit tissue, as a specific treatment or while preparing skin discs, increased the level of anthocyanin in the skin and replaced the stimulating effect on anthocyanin formation of applied u.v. light or cycloheximide. The effects of wounding and cycloheximide decreased with increasing fruit maturity. The data suggested that wounding, u.v. light, maturity and cycloheximide act through a common effector, perhaps ethylene.