Multiomics analyses of the effects of LED white light on the ripening of apricot fruits

Apricot (Prunus armeniaca L.) fruits are highly perishable and prone to quality deterioration during storage and transportation. To investigate the effects of LED white light treatment on postharvest ripening of fruits using metabolomics, transcriptomics, and ATAC-Seq analysis. Fruits were exposed to 5 μmol m-2 s-1 LED white light for 12 hours followed by 12 hours of darkness at 20 °C daily for 12 days. The effects of the treatments on the physiological and nutritional quality of the fruits were evaluated. These data were combined with transcriptomic, metabolomic, and ATAC-Seq data from fruits taken on Day 8 of treatment to provide insight into the potential mechanism by which LED treatment delays ripening. LED treatment activated pathways involved in ascorbate and aldarate metabolism and flavonoid and phenylpropanoid biosynthesis. Specifically, LED treatment increased the expression of UDP-sugar pyrophosphorylase (USP), L-ascorbate peroxidase (AO), dihydroflavonol 4-reductase (DFR), chalcone synthase (CHS), and caffeoyl-CoA O-methyltransferase (CCOAOMT1), leading to the accumulation of caffeoyl quinic acid, epigallocatechin, and dihydroquercetin and the activation of anthocyanin biosynthesis. LED treatment also affected the expression of genes associated with plant hormone signal transduction, fruit texture and color transformation, and antioxidant activity. The notable genes affected by LED treatment included 1-aminocyclopropane-1-carboxylate synthase (ACS), 1-aminocyclopropane-1-carboxylate oxidase (ACO), hexokinase (HK), lipoxygenase (LOX), malate dehydrogenase (MDH), endoglucanase (CEL), various transcription factors (TCP, MYB, EFR), and peroxidase (POD). ATAC-Seq analysis further revealed that LED treatment primarily regulated phenylpropanoid biosynthesis. The results obtained in this study provide insights into the effects of LED light exposure on apricot fruit ripening. LEDs offer a promising approach for extending the shelf life of other fruits and vegetables.