8 research outputs found
Physiological and proteomic approaches to address the active role of ozone in kiwifruit post-harvest ripening
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
Effect of ozone application during cold storage of kiwifruit on the development of stem-end rot caused by Botrytis cinerea
The effect of gaseous ozone exposure on the development of stem-end rot disease, caused by Botrytis cinerea, on kiwifruit (Actinidia deliciosa, cv. Hayward) was investigated. Artificially inoculated kiwifruit were subjected for 4 months to conventional cold storage (0 °C, RH 95%) where catalytic oxidation of ethylene was applied (control) and to conventional cold storage with continuous supply of ozone (0.3 μL L−1) or in a conventional kiwifruit cold storage room, where catalytic oxidation of ethylene was applied. Ozone treatment delayed and simultaneously decreased disease incidence by 56%, while disease severity on infected fruit remained unaffected. Infected fruit formed sclerotia, while no sporulation of the pathogen occurred in the presence of ozone. To elucidate whether the observed disease suppression was mediated by a direct effect of ozone on the fungal pathogen per se or by the induction of a resistance mechanism in the fruit, two additional sets of experiments were conducted. Kiwifruit were exposed to ozone (0.3 μL L−1) for 0, 2, 8, 24, 72 and 144 h in a conventional cold storage room either before or after the artificial inoculation with the pathogen and its efficacy on disease incidence and severity was monitored. Pre-inoculation exposure of fruit to ozone, at increasing exposure time intervals led to significant suppression of disease incidence, while post-inoculation exposure did not affect it. The observed disease suppression, provided by the pre-inoculation exposure, strongly suggests that ozone treatments induce resistance of kiwifruit to the pathogen. Measurements of antioxidant substances and antioxidant activity on fruit exposed to ozone for the same time intervals showed a strong negative correlation between disease incidence or severity and phenol content
Ozone-induced inhibition of kiwifruit ripening is amplified by 1-methylcyclopropene and reversed by exogenous ethylene
Abstract Background Understanding the mechanisms involved in climacteric fruit ripening is key to improve fruit harvest quality and postharvest performance. Kiwifruit (Actinidia deliciosa cv. ‘Hayward’) ripening involves a series of metabolic changes regulated by ethylene. Although 1-methylcyclopropene (1-MCP, inhibitor of ethylene action) or ozone (O3) exposure suppresses ethylene-related kiwifruit ripening, how these molecules interact during ripening is unknown. Results Harvested ‘Hayward’ kiwifruits were treated with 1-MCP and exposed to ethylene-free cold storage (0 °C, RH 95%) with ambient atmosphere (control) or atmosphere enriched with O3 (0.3 μL L− 1) for up to 6 months. Their subsequent ripening performance at 20 °C (90% RH) was characterized. Treatment with either 1-MCP or O3 inhibited endogenous ethylene biosynthesis and delayed fruit ripening at 20 °C. 1-MCP and O3 in combination severely inhibited kiwifruit ripening, significantly extending fruit storage potential. To characterize ethylene sensitivity of kiwifruit following 1-MCP and O3 treatments, fruit were exposed to exogenous ethylene (100 μL L− 1, 24 h) upon transfer to 20 °C following 4 and 6 months of cold storage. Exogenous ethylene treatment restored ethylene biosynthesis in fruit previously exposed in an O3-enriched atmosphere. Comparative proteomics analysis showed separate kiwifruit ripening responses, unraveled common 1-MCP- and O3-dependent metabolic pathways and identified specific proteins associated with these different ripening behaviors. Protein components that were differentially expressed following exogenous ethylene exposure after 1-MCP or O3 treatment were identified and their protein-protein interaction networks were determined. The expression of several kiwifruit ripening related genes, such as 1-aminocyclopropane-1-carboxylic acid oxidase (ACO1), ethylene receptor (ETR1), lipoxygenase (LOX1), geranylgeranyl diphosphate synthase (GGP1), and expansin (EXP2), was strongly affected by O3, 1-MCP, their combination, and exogenously applied ethylene. Conclusions Our findings suggest that the combination of 1-MCP and O3 functions as a robust repressive modulator of kiwifruit ripening and provide new insight into the metabolic events underlying ethylene-induced and ethylene-independent ripening outcomes
Ozone-induced kiwifruit ripening delay is mediated by ethylene biosynthesis inhibition and cell wall dismantling regulation
Ozone treatments are used to preserve quality during cold storage of commercially important fruits due to its ethylene oxidizing capacity and its antimicrobial attributes. To address whether or not ozone also modulates ripening by directly affecting fruit physiology, kiwifruit (Actinidia deliciosa cv. ‘Hayward’) were stored in very low ethylene atmosphere at 0 °C (95% RH) in air (control) or in the presence of ozone (0.3 μL L−1) for 2 or 4 months and subsequently ripened at 20 °C (90% RH) for up to 8 d. Ozone-treated kiwifruit showed a significant delay of ripening during maintenance at 20 °C, accompanied by a marked decrease in ethylene biosynthesis due to inhibited AdACS1 and AdACO1 expression and reduced ACC synthase (ACS) and ACC oxidase (ACO) enzyme activity. Furthermore, ozone-treated fruit exhibited a marked reduction in flesh softening and cell wall disassembly. This effect was associated with reduced cell wall swelling and pectin and neutral sugar solubilization and was correlated with the inhibition of cell wall degrading enzymes activity, such as polygalacturonase (PG) and endo-1,4-β-glucanase/1,4-β-glucosidase (EGase/glu). Conclusively, the present study indicated that ozone may exert major residual effects in fruit ripening physiology and suggested that ethylene biosynthesis and cell walls turnover are specifically targeted by ozone