Transcriptome sequencing reveals mechanism of improved antioxidant capacity and maintained postharvest quality of winter jujube during cold storage after salicylic acid treatment

Harvested winter jujube fruit undergo rapid senescence and oxidation, which seriously affects their commercialization. This study aimed to investigate the effects of exogenous salicylic acid (SA) treatment on postharvest quality, antioxidant systems, and differential expressed genes (DEGs) of winter jujube during cold storage. We found SA treatment delayed weight loss and decay, inhibited respiratory rate and ethylene production, and maintained higher activities of superoxide dismutase, catalase, ascorbic acid peroxidase, and glutathione reductase. It also increased contents of phenols, flavonoids, ascorbic acid, and reduced glutathione. Transcriptome analysis showed that the DEGs in comparison groups were mainly involved in metabolic pathways, secondary metabolic biosynthesis, and plant hormone signal transduction. SA treatment up-regulated the antioxidant-related genes (SOD1/3, GRXC2, APX1, and CTV5), and also participated in the regulation of plant hormone signaling related genes (ABF4, SnRK2, PYL2, PP2C, MKK4, ERF, EBF2 and JAZ), senescence associated genes (PME15, CTL2, INVE, ADH2, SAG21, SRK2H and ATG4), and transcription factors (MYB, ERF, C2H2, MTB3, WRKY, and FAR1). Therefore, we concluded that exogenous SA could enhance the antioxidant systems and maintain storage quality by regulating related gene expressions and metabolic pathways. These results contribute to understand the mechanism of delaying ripening and senescence of winter jujube.