The impact of sodium nitroprusside and ozone in kiwifruit ripening physiology: A combined gene and protein expression profiling approach

Abstract

Background and Aims Despite their importance in many aspects of plant physiology, information about the function of oxidative and, particularly, of nitrosative signalling in fruit biology is limited. This study examined the possible implications of O<inf>3</inf> and sodium nitroprusside (SNP) in kiwifruit ripening, and their interacting effects. It also aimed to investigate changes in the kiwifruit proteome in response to SNP and O<inf>3</inf> treatments, together with selected transcript analysis, as a way to enhance our understanding of the fruit ripening syndrome. Methods Kiwifruits following harvest were pre-treated with 100∈μm SNP, then cold-stored (0°C, relative humidity 95%) for either 2 or 6 months in the absence or in the presence of O<inf>3</inf> (0·3∈μL L-1), and subsequently were allowed to ripen at 20°C. The ripening behaviour of fruit was characterized using several approaches: together with ethylene production, several genes, enzymes and metabolites involved in ethylene biosynthesis were analysed. Kiwifruit proteins were identified using 2-D electrophoresis coupled with nanoliquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Expression patterns of kiwifruit ripening-related genes were also analysed using real-time quantitative reverse transcription-PCR (RT-qPCR). Key Results O<inf>3</inf> treatment markedly delayed fruit softening and depressed the ethylene biosynthetic mechanism. Although SNP alone was relatively ineffective in regulating ripening, SNP treatment prior to O<inf>3</inf> exposure attenuated the O<inf>3</inf>-induced ripening inhibition. Proteomic analysis revealed a considerable overlap between proteins affected by both SNP and O<inf>3</inf>. Consistent with this, the temporal dynamics in the expression of selected kiwifruit ripening-related genes were noticeably different between individual O<inf>3</inf> and combined SNP and O<inf>3</inf> treatments. Conclusions This study demonstrates that O<inf>3</inf>-induced ripening inhibition could be reversed by SNP and provides insights into the interaction between oxidative and nitrosative signalling in climacteric fruit ripening. © 2015 The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company.