Comparative transcriptomic profiling of peach and nectarine cultivars reveals cultivar-specific responses to chilled postharvest storage

Abstract

IntroductionPeach (Prunus persica (L.) Batsch,) and nectarine fruits (Prunus persica (L.) Batsch, var nectarine), are characterized by a rapid deterioration at room temperature. Therefore, cold storage is widely used to delay fruit post-harvest ripening and extend fruit commercial life. Physiological disorders, collectively known as chilling injury, can develop typically after 3 weeks of low-temperature storage and affect fruit quality.MethodsA comparative transcriptomic analysis was performed to identify regulatory pathways that develop before chilling injury symptoms are detectable using next generation sequencing on the fruits of two contrasting cultivars, one peach (Sagittaria) and one nectarine, (Big Top), over 14 days of postharvest cold storage.ResultsThere was a progressive increase in the number of differentially expressed genes between time points (DEGs) in both cultivars. More (1264) time point DEGs were identified in ‘Big Top’ compared to ‘Sagittaria’ (746 DEGs). Both cultivars showed a downregulation of pathways related to photosynthesis, and an upregulation of pathways related to amino sugars, nucleotide sugar metabolism and plant hormone signal transduction with ethylene pathways being most affected. Expression patterns of ethylene related genes (including biosynthesis, signaling and ERF transcription factors) correlated with genes involved in cell wall modification, membrane composition, pathogen and stress response, which are all involved later during storage in development of chilling injury.DiscussionOverall, the results show that common pathways are activated in the fruit of ‘Big Top’ nectarine and ‘Sagittaria’ peach in response to cold storage but include also differences that are cultivar-specific responses.

Prunus spp. Fruit Quality and Postharvest: Today’s Challenges and Future Perspectives

“…The following ripening parameters are usually considered in peaches: firmness (measured in Newton, as the maximum force needed to penetrate the fruit), skin colour, soluble solids content (SSC), (measured in °Brix), titratable acidity (TA) (measured in %) and the ratio SSC/TA, which is sometimes used as a maturity index [36,37]. The criteria used for quality evaluation of peaches take into account the Prunus spp.…”

“…Cold storage is the most common method employed to delay ripening and increase the postharvest life of peaches [42]. Peaches are ideally kept at around 0°C, but a range of −1 to 1°C is acceptable for up to 2 to 3 weeks [37,43]. However, prolonged storage at low temperatures may change the ripening processes and result in lack of juice and woolly texture [42].…”

“…A recent study evaluated the transcriptomic profile of peaches upon postharvest cold storage [37]. Expression levels of ethylene related genes are correlated with genes involved in cell wall modification, membrane composition, pathogen and stress response, which are all involved in the development of chilling injury [37]. Moreover, early transcriptomic responses to chilling are detectable well before the onset of chilling injury symptoms.…”

“…Moreover, early transcriptomic responses to chilling are detectable well before the onset of chilling injury symptoms. Genes that are activated early upon cold storage may provide markers for detecting chilling injury before it can be perceived visually [37].…”

Biochemical and molecular changes in peach fruit exposed to cold stress conditions

“…Weighted gene correlation network analysis is also a useful tool to explore co-expression networks to try to identify upstream regulators for genes known to be implicated in CI. For example, this approach identified potential ERF regulators of CI-related genes that are up-regulated very early during chilled storage (Muto et al 2022a ). Further analysis of promoter function has also been addressed through new tools to identify motifs associated with particular expression patterns (Ksouri et al 2021 ).…”