Comparative “phenol-omics” and gene expression analyses in peach (Prunus persica) skin in response to different postharvest UV-B treatments

Abstract Ultraviolet-B (UV B) radiation impacts the plant behaviour in many ways, including modifying their secondary metabolism. Although several studies have quantified the UV-B effects on phenoliccomposition, most of them focused on leaves or investigated a limited amount of phenolics. The present work aimed to investigate the phenolicchanges after two postharvest UV-B treatments, 10 and 60 min (1.39 kJ m −2 and 8.33 kJ m −2 , respectively), on peach ( Prunuspersica cv Fairtime) fruit with a non-targeted, whole profiling approach, and targeted gene expression analysis on skin. After both UV-B exposures, peach fruit were harvested at 24 and 36 h for “ phenol- omics” analysis, while additional 6 h and 12 h recovery times were used for gene expression analysis. Our results revealed that both UV-B exposures resulted in a decrease of several phenoliccompounds, such as anthocyanins, after 24 h from the exposure. In contrast, the expression of the UV-B signalling components, the phenylpropanoidbiosynthesis genes and their transcriptional regulators increased 6 h after the treatment, mostly with a UV-B-dose dependent behaviour, preceding an accumulation of most phenolicsin both the UV-B treatments at 36 h compared to 24 h. Orthogonal projections to latent structures discriminant analysis ( OPLS-DA) revealed that flavonoids, particularly anthocyanins, were the main phenolicsubclasses accumulated after UV-B exposure.