Active compound analysis of Ziziphus jujuba cv. Jinsixiaozao in different developmental stages using metabolomic and transcriptomic approaches

Jujube (Ziziphus jujuba Mill.) is a popular fruit with health benefits ascribed to its various metabolites. These metabolites determine the flavors and bioactivities of the fruit, as well as their desirability. However, the dynamics of the metabolite composition and the underlying gene expression that modulate the overall flavor and accumulation of active ingredients during fruit development remain largely unknown. Therefore, we conducted an integrated metabolomic and transcriptomic investigation covering various developmental stages in the jujube cultivar Z. jujuba cv. Jinsixiaozao, which is famous for its nutritional and bioactive properties. A total of 407 metabolites were detected by non-targeted metabolomics. Metabolite accumulation during different jujube developmental stages was examined. Most nucleotides and amino acids and their derivatives accumulated during development, with cAMP increasing notably during ripening. Triterpenes gradually accumulated and were maintained at high concentrations during ripening. Many flavonoids were maintained at relatively high levels in early development, but then rapidly decreased later. Transcriptomic and metabolomic analyses revealed that chalcone synthase (CHS), chalcone isomerase (CHI), flavonol synthase (FLS), and dihydroflavonol 4-reductase (DFR) were mainly responsible for regulating the accumulation of flavonoids. Therefore, the extensive downregulation of these genes was probably responsible for the decreases in flavonoid content during fruit ripening. This study provide an overview of changes of active components in 'Jinsixiaozao' during development and ripening. These findings enhance our understanding of flavor formation and will facilitate jujube breeding for improving both nutrition and function.