Effects of low‐temperature conditioning and cold storage on development of chilling injuries and the transcriptome of ‘Wonderful’ pomegranate fruit

Abstract

SummaryWe recently developed a postharvest low‐temperature‐conditioning (LTC) treatment for ‘Wonderful’ pomegranate fruits that involve prestorage exposure to 15 °C for 10 days, and it markedly enhanced chilling tolerance. To elucidate the molecular mechanisms involved in the fruit responses to LTC, we conducted RNA‐Seq analysis of ‘Wonderful’ pomegranate inner membrane tissue at four different time points: (i) immediately after harvest; (ii) after the LTC treatment; (iii) after 2 weeks of cold storage at 1 °C; and (iv) after LTC + 2 weeks at 1 °C. Pairwise comparisons revealed that 7798 transcripts were significantly (P ≤ 0.05) induced or repressed by a factor of at least four in the chilling treatment (2422 upregulated and 5376 downregulated) as compared with just 1997 transcripts in the LTC + chilling treatment (974 upregulated and 1023 downregulated). Thus, application of LTC mitigated the overall changes in transcript levels associated with cold storage. Furthermore, the LTC + chilling affected gene expression patterns related to regulatory and stress mechanisms, including modification of specific transcription factor, signalling and stress‐related genes.