The interaction between nitric oxide with ozone regulate kiwifruit postharvest physiology

Ozone (O3) has been shown to extend kiwifruit (Actinidia deliciosa cv. ?Hayward?) ripening by down-regulating fruit ethylene emission, whereas nitric oxide (NO) has been suggested to delay fruit senescence. This study focuses on developing a set of postharvest O3 and NO treatments to control kiwifruit postharvest ripening and to provide insights into O3 and NO mode of action. To address this, kiwifruit were pre-treated with 100 ?? sodium nitroprusside (SNP, a NO donor), then were cold-stored (0?C, RH 95%) for up to 6 months in the absence or in the presence of ozone (0.3 ?L L-1), and subsequently were allowed to ripen for up to 8 days at 20oC (shelf-life). Physiological data showed that NO seems to act upstream of the ozone action since ethylene production was strongly inhibited by ozone only in the absence of SNP application, whereas kiwifruit exposed to both chemicals (SNP+O3 treatment) displayed the phenotype of control fruits.Furthermore, watery areas, the typical symptoms of kiwifruit flesh breakdown due to over-ripening, were observed only following SNP pre-treatment testifying that NO promotes kiwifruit senescence and shortens its postharvest shelf-life. The intracellular NO production in kiwifruit was real-time monitored by confocal laser scanning microscopy (CLMS) analysis using the fluorescent probe 4,5-diaminofluorescin diacetate (DAF-2DA). Various components of ethylene biosynthetic pathway, including ACC synthase (ACS) and ACC oxidase (ACO) enzyme activities and genes expression (ACS1 and ACO1, respectively), and the content of 1-aminocyclopropane-1-carboxylic acid(ACC) and 1-malonyl-ACC (MACC) were remarkably regulated by both ozone and SNP. In addition, the expression of various genes involved in kiwifruit ripening process, such as lipoxygenase (LOX1), geranylgeranylbiphosphate synthase (GGP1), ethylene receptor (ETR1), polyphenoloxidase (PPO), bet v 1 related allergen, malate dehydrogenase (MDH), polugalactorunase (PG), sucrose synthetase (SS)and3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) were affected by ozone, while NO has either a complementary or negative regulator of this ozone function. Proteomic analysis using two-dimensional gel electrophoresis (2DE-PAGE) followed by nanoscale liquid chromatography coupled to tandem mass spectrometry (nanoLC-MS/MS-LTQ-Velos-Orbitrap) revealed significant changes in response to SNP (12 proteins), O3 (22 proteins) and SNP+O3 (41 proteins) treatments in comparison to control. Among the 41 proteins and the 22 proteins changed in response to SNP+O3 and to O3, respectively, only 14 proteins are commonly modulated (in the same way; up or down regulation).Meanwhile, 26 proteins are exclusively targeted by the SNP+O3treatment, indicating that NO has multiple biological effects on O3-treated fruit. All kiwifruit proteins identified are functionally classified to metabolic pathway and its specific role was characterized. SourcesThe interaction between nitric oxide with ozone regulate kiwifruit postharvest physiologyG. Tanou1,2, I.S. Minas1, E. Karagiannis1, M. Belghazi3, D.Tsikou2, K.K. Papadopoulou2, A.N. Molassiotis11Departmentof Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece2Department of Biochemistry & Biotechnology, University of Thessaly, 41221 Larissa, Greece3Proteomics Analysis Center (CAPM), Faculty of Medicine, 13916 Marseilles, FranceV Postharvest Unlimited, ISHS International Conference, 10-13 June 2014, Cyprus, http://web.cut.ac.cy/postharvest/