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

Summary We 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.