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.

Jujube metabolome selection determined the edible properties acquired during domestication.

Plants supply both food and medicinal compounds, which are ascribed to diverse metabolites produced by plants. However, studies on domestication-driven changes in the metabolome and genetic basis of bioactive molecules in perennial fruit trees are generally lacking. Here, we conducted multidimensional analyses revealing a singular domestication event involving the genomic and metabolomic selection of jujube trees (Ziziphus jujuba Mill.). The genomic selection for domesticated genes was highly enriched in metabolic pathways, including carbohydrates and specialized metabolism. Domesticated metabolome profiling indicated that 187 metabolites exhibited significant divergence as a result of directional selection. Malic acid was directly selected during domestication, and the simultaneous selection of specialized metabolites, including triterpenes, consequently lead to edible properties. Cyclopeptide alkaloids (CPAs) were specifically targeted for the divergence between dry and fresh cultivars. We identified 1080 significantly associated loci for 986 metabolites. Among them, 15 triterpenes were directly selected at six major loci, allowing the identification of a homologous cluster containing seven 2,3-oxidosqualene cyclases (OSCs). An OSC gene was found to contribute to the reduction in the content of triterpenes during domestication. The complete pathway for synthesizing ursolic acid was dissected by integration of the metabolome and transcriptome. Additionally, an N-methyltransferase involved in the biosynthesis of CPA and responsible for inter-cultivar content variation was identified. The present study promotes our understanding of the selection process of the global metabolome subsequent to fruit tree domestication and facilitates the genetic manipulation of specialized metabolites to enhance their edible traits.