Transcriptome Responses of Ripe Cherry Tomato Fruit Exposed to Chilling and Rewarming Identify Reversible and Irreversible Gene Expression Changes

Fruit of cherry tomato , Solanum lycopersicum var. cerasiforme L, were obtained from a packhouse at commercial ripeness during the middle of the production season in 2018 and 2019. Plastic clamshell punnets each containing 20 to 23 fruit arrived at the research facility the day after packing, and were stored overnight at 20C. In each of the two experiments, one set of replicates was processed after the overnight storage at 20C. In the first experiment , storage at three different temperatures was compared. One set of punnets was maintained at 20C for 6 d to study development at a typical shelf temperature. Half the remaining punnets were placed in cold storage at 10C and the other half at 4C, representing mild and severe chilled storage conditions, respectively. Samples were removed at 6 d and 27 d, with further sets of replicates stored for 27 d plus an additional 1 d and 6 d at 20C. In the second experiment , the focus was on earlier molecular responses to chilling temperature. Punnets were stored at 4C, with replicates removed after 1, 4, 12 and 19 d. Additional replicates were removed at 12 and 19 d and transferred to 20C for 7 d. At each temperature and time point, analysis was carried out using three biological replicates.