Effects of low-temperature storage on the aroma composition and quality of Golden Empress Hami melons: A transcriptomic and metabolomic analysis

Abstract

Low-temperature storage is frequently employed to prolong the shelf life of Hami melons. Nevertheless, extended low-temperature storage can hamper the synthesis of aroma compounds in these fruits. This study investigated the effects of storage at 3 °C (LT) and 21 °C (RT) on the aroma quality of Golden Empress Hami melons (GEHMs) during a shelf life of 24 d. Further, the transcription levels of genes related to aroma metabolism were also examined during this period. After 12 d, the intensity of sweet aroma (LT: 2.3, RT: 8.2) and fruit aroma (LT: 2.1, RT: 8) was significantly lower in GEHMs stored at LT than in those stored at RT. Correspondingly, between-group differences in the content of esters with sweet and fruity aromas (RT: 782.76 ± 128.41 μg/kg, LT: 53.69 ± 24.32 μg/kg) and alcohols (RT: 2252.98 ± 297.65 μg/kg, LT: 448.80 ± 106.13 μg/kg) peaked at 12 d. Furthermore, the expression levels of 52 genes related to aroma volatile biosynthesis were significantly different between GEHMs stored at RT and LT. Specifically, the expression levels of genes encoding ethanol dehydrogenase (ADH), long-chain acyl-CoA synthetase (ACSL), and branched-chain amino acid aminotransferase (ilvE) which are involved in the production of alcohols and esters— were significantly lower in GEHMs stored at LT than in those stored at RT. This study provides a deeper understanding of aroma-related biosynthetic pathways of GEHMs during postharvest storage. Additionally, it offers valuable metabolomic and transcriptomic resources for the regulation of aroma compound metabolism in postharvest GEHMs.