Both ozone and 1-MCP postharvest application delay flesh softening and soluble solids content increase in kiwi

Emerging evidence suggests that the post-harvest ozone application inhibits the onset of ripening in kiwifruit (Actinidia deliciosa, cv. ?Hayward?); however, the exact mechanism of ozone action is not yet fully elucidated. In addition, it has been reported that 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action, delays kiwifruit ripening and prolongs its postharvest life. In the present study, kiwifruit following commercial harvest were treated with 1-MCP and exposed to ethylene-free cold storage (0?C, RH 95%) in the absence (control) or in the presence of ozone (0.3 ?L L-1) for 2 or 6 months and subsequently were allowed to ripen at 20?C. Data revealed that both ozone and 1-MCP postharvest application (1-MCP + ozone treatment) were able to inhibit endogenous ethylene production and the accumulation of its intermediates, 1-aminocyclopropane-1 carboxylic acid (ACC) and 1-malonyl-ACC (MACC), during kiwifruit ripening at 20?C, as well as to delay flesh softening and soluble solids content increase compared to control fruit. The combination of 1-MCP and ozone treatments caused the stronger inhibition on kiwifruit ripening process, resulting to remarkably extension (by 1.5 to 2 months) in fruit storage potential compared to the individual treatments. In order to define whether the effect of ozone on kiwifruit ripening is a result of an oxidative damage on ethylene biosynthesis mechanism or a biochemical inhibition, fruit were treated with external ethylene (100 ?L L-1, 24 h) upon removal to 20?C, following 6 months of cold storage. It was evidenced that external ethylene treatment caused a rapid increase in ?autocatalytic? ethylene production in the fruit that previously was stored in an ozone-enriched atmosphere. The expression of several genes involved in kiwifruit ripening process,such as ACC synthase (ACS1), ACC oxidase (ACO1), ethylene receptor (ETR1), lipoxygenase(LOX1), geranylgeranylbiphosphate synthase (GGP1), expansine (EXP2) was specifically affected by ozone, 1-MCP and their combination, while the treatment with external ethylene differentially regulated the expression of these genes. Proteomic analysis, using two-dimensional gel electrophoresis (2DEPAGE) and nanoscale liquid chromatography coupled to tandem mass spectrometry (nano LC-MS/MS), indicated that the postharvest treatments applied (1-MCP, ozone, 1-MCP + ozone) modulated the abundance of 51 protein spots of the kiwifruit proteomic map, while external ethylene treatment changed the abundance of 99 proteins spots in fruits exposed to all treatments. Overall, this study provides new insights into pathways involved in kiwifruit ripening regulation mechanism. SourcesThe physiological and molecular impact of ozone and 1-methylcyclopropene on kiwifruit postharvest ripeningI.S. Minas1, G. Tanou1, M. Belghazi2, A. Krokida3, M. Vasilakakis1, K.K. Papadopoulou3, A.N. Molassiotis11Department of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece2Proteomics Analysis Center (CAPM), Faculty of Medicine, 13916 Marseilles, France3Department of Biochemistry & Biotechnology, University of Thessaly, 41221 Larissa, Greece V Postharvest Unlimited, ISHS International Conference, 10-13 June 2014, Cyprus, http://web.cut.ac.cy/postharvest/ Picture by vidasanafacil.com