Cold storage of fruit may induce the physiological disorder chilling injury (CI); however, the molecular basis of CI development remains largely unexplored. Simulated conditions of CI priming and suppression provided an interesting experimental system to study cold response in fruit. Peaches (cv. June Gold) at the commercial harvest (CH) or tree-ripe (TR) stages were immediately exposed to cold treatment (40 d, 0 °C) and an additional group of CH fruits were pre-conditioned 48 h at 20 °C prior to low-temperature exposure (pre-conditioning, PC). Following cold treatment, the ripening behaviour of the three groups of fruits was analysed (3 d, 20 °C). Parallel proteomic, metabolomic and targeted transcription comparisons were employed to characterize the response of fruit to CI expression. Physiological data indicated that PC suppressed CI symptoms and induced more ethylene biosynthesis than the other treatments. Differences in the protein and metabolic profiles were identified, both among treatments and before and after cold exposure. Transcriptional expression patterns of several genes were consistent with their protein abundance models. Interestingly, metabolomic and gene expression results revealed a possible role for valine and/or isoleucine in CI tolerance. Overall, this study provides new insights into molecular changes during fruit acclimation to cold environment.

Post-harvest ozone application has recently been shown to inhibit the onset of senescence symptoms on fleshy fruit and vegetables; however, the exact mechanism of action is yet unknown. To characterize the impact of ozone on the post-harvest performance of kiwifruit (Actinidia deliciosa cv. ‘Hayward’), fruits were cold stored (0 °C, 95% relative humidity) in a commercial ethylene-free room for 1, 3, or 5 months in the absence (control) or presence of ozone (0.3 μl l⁻¹) and subsequently were allowed to ripen at a higher temperature (20 °C), herein defined as the shelf-life period, for up to 12 days. Ozone blocked ethylene production, delayed ripening, and stimulated antioxidant and anti-radical activities of fruits. Proteomic analysis using 1D-SDS-PAGE and mass spectrometry identified 102 kiwifruit proteins during ripening, which are mainly involved in energy, protein metabolism, defence, and cell structure. Ripening induced protein carbonylation in kiwifruit but this effect was depressed by ozone. A set of candidate kiwifruit proteins that are sensitive to carbonylation was also discovered. Overall, the present data indicate that ozone improved kiwifruit post-harvest behaviour, thus providing a first step towards understanding the active role of this molecule in fruit ripening.