Postharvest heat and CO2 shocks induce changes in cuticle composition and cuticle-related gene expression in ‘October Sun’ peach fruit

Abstract

Fruit cuticles influence greatly postharvest quality of produce. Yet, few published studies have addressed changes in cuticle composition and related gene expression from a postharvest perspective, particularly for fruit species within the Rosaceae family. Because physical treatments have proved effective in improving postharvest potential in some commodities, we were interested in assessing whether such benefits could arise, at some extent, from treatment-related alterations in cuticular components. In this work, commercially ripe ‘October Sun’ peaches were submitted to heat or CO2 shocks, and then stored at 0 °C for two weeks followed by five days at 20 °C. Wax and cutin composition was analyzed from cuticle samples isolated enzymatically from fruit skin, and expression of selected genes PpCER1, PpLACS1 and PpLipase, putatively involved in cuticle deposition, was quantified by quantitative real-time PCR. The amount (g m−2) of the main cuticular wax families identified was higher in treated fruit in comparison with the controls, particularly after the shelf life period. Treatment influence on cutin composition was less clear. Gene expression was generally impaired under cold storage, to recover to a variable extent upon transfer to 20 °C. The differential gene expression shown in response to treatments may relate to the observed compositional changes in the cuticle.