Transcription Factors ZjMYB39 and ZjMYB4 Regulate Farnesyl Diphosphate Synthase- and Squalene Synthase-Mediated Triterpenoid Biosynthesis in Jujube.

Jujube ( Mill.) is rich in valuable bioactive triterpenoids. However, the regulatory mechanism underlying triterpenoid biosynthesis in jujube remains poorly studied. Here, we characterized the triterpenoid content in wild jujube and cultivated jujube. The triterpenoid content was higher in wild jujube than in cultivated jujube, triterpenoids were most abundant in young leaves, buds, and later stages of development. The transcriptome analysis and correlation analysis showed that differentially expressed genes (DEGs) were enriched in the terpenoid synthesis pathways, and triterpenoids content was strongly correlated with farnesyl diphosphate synthase (), squalene synthase (), and transcription factors and expression. Gene overexpression and silencing analysis indicated that and were key genes in triterpenoid biosynthesis and transcription factors and regulated triterpenoid biosynthesis. Subcellular localization experiments showed that and were localized to the nucleus and endoplasmic reticulum and and were localized to the nucleus. Yeast one-hybrid, glucuronidase activity, and dual-luciferase activity assays suggested that and regulate triterpenoid biosynthesis by directly binding and activating the promoters of and . These findings provide insights into the underlying regulatory network of triterpenoids metabolism in jujube and lay theoretical and practical foundation for molecular breeding.