Fruit quality and differentially expressed genes of winter-harvested pineapple in response to elevated temperature over a short postharvest period

The aim of this work was to investigate the influences of elevated postharvest temperature (EPT) for 1 d and 2 d on the physicochemical quality of pineapple fruit and the differentially expressed genes (DEGs) underlying this process by RNA-seq. The results suggested that EPT increased the L*, a*, b* of pineapple fruit skin. EPT decreased the L* and increased the a* and b* of pineapple pulp. EPT increased the total soluble solid (TSS), sucrose content and TSS/titratable acidity (TA) ratio and decreased the TA. EPT decreased the firmness of pineapple fruit. At 1 d, EPT improved the production of aromatic alkenes. At 2 d, EPT improved the production of aromatic esters and decreased the alkenes. A differential gene expression analysis suggested that a total of 6725 and 5845 DEGs were identified by comparing EPT and control at 1 d and 2 d, respectively. A number of DEGs were screened for their involvement in the EPT process effects on pineapple fruit, including those associated with coloration, sugar/acid metabolism, texture softening and aroma biosynthesis. A subset of these DEGs was validated by qPCR, which was consistent with the corresponding Reads Per Kilo bases per Million reads (RPKM values) from RNA-seq. The findings of this study contribute to our understanding of how EPT regulates the quality of pineapple fruit over different durations and the molecular mechanisms underlying this process.