Augmented analysis of sensorial, volatilome and gene expression data from peach cultivars during cold storage to identify markers for fruit quality

Peach (Prunus persica (L. Batsch) produces high quality but perishable fruit appreciated for their distinctive aroma, and other organoleptic qualities including sweetness, colour, and texture which vary across different cultivars. Peaches are produced commercially in warmer temperate regions such as Southern Europe, and frequently exported to Northern Europe. Due to the long travel distances and complex supply chains peach fruit are transported cold to delay ripening and spoilage. However long periods of cold storage can result in chilling injury and loss of quality. Our understanding of how cold storage affects quality across different varieties can be explored through different approaches. Here effects were assessed in one peach ('Sagittaria') and one nectarine cultivar ( 'Big Top') through volatilome fingerprinting combined with gene expression profiling. For analysis of the volatile organic compounds (VOCs) contributing to the volatilome, we applied two-dimensional gas chromatography (GC×GC) combined with time-of-flight mass spectrometry (TOF-MS), as well as sensorial analysis. RNA-sequencing was applied to identify differentially expressed genes (DEGs) during post-harvest storage focusing on genes associated with VOCs. Peach fruits were analysed at harvest and during 14 days of cold storage at 1°C. Different numbers of VOCs were identified in the two cultivars: of 159 from ‘Sagittaria’, and 89 from ‘Big Top’ fruit. Canonical Analysis of Principal coordinates (or CAP) was able to discriminate amongst VOC profiles from the two cultivars and across post-harvest storage time points. A multitrait analysis of sensory, VOC and gene expression data supported the analysis based only on VOCs showing correlations between the expression profiles of VOC-related genes and VOC abundance. These data are of potential use to peach breeders for improving cold storage resilience in relation to sensory changes, and could form the basis for markers of use in assessing fruit quality through the supply chain.