Regulatory network of flavonoids, phenolic acids and terpenoids biosynthesis in Zizyphus jujuba Mill. cv. Goutou jujube fruits

Abstract

Flavonoids, phenolic acids and terpenoids are important active ingredients that are biomarkers for evaluating the quality of Zizyphus jujuba Mill. Cv. Goutou jujube fruit. Nevertheless, regulatory network of these active ingredients biosynthesis in jujube fruit is still unclear. Here, integrated metabolomics and transcriptomics analyses were conducted at four different stages during the ripening of jujube fruits. Cytochrome P450 enzymes (CYP450s) and uridine 5′-diphospho-glucuronosyltransferases (UGTs) are pivotal enzymes for flavonoids, phenolic acids and terpenoids biosynthesis in plants. Benzoylmalic acid, a phenolic acid, 4′, 5, 7-trihydroxyflavanon and quercetin-3-O-(6″-p-coumaroyl), two flavonoid metabolites, and jujuboside B1, a triterpenoid metabolite were targeted as they were correlated with both CYP450s and UGTs. Furthermore, networks of TFs, CYP450s and UGTs involved in the target metabolites biosynthesis were elucidated. NAC_1 and bZIP2 up-regulated CYP71A7 expression, while G2-like2 and bHLH_1 positively regulated the CSE expression contributing to promoted benzoylmalic acid biosynthesis. G2-like2, bHLH_1 and bHLH_2 indicated a positive relationship with CYP93D1, CYP86C2/3 or UGT71A16 which were positively correlated with 4′, 5, 7-trihydroxyflavanon biosynthesis. MYB1/2/3, C2H2_2 and WRKY positively regulated expression of CYP82A4 or UGT_1 resulted in increased quercetin-3-O-(6″-p-coumaroyl) galactoside biosynthesis. G2-like2 and bHLH_1 up-regulated 4 C L, CYP93D1 or UGT71A16 was the reason for an increase of jujuboside B1 biosynthesis. The findings provide new insight into molecular breeding of high-quality jujube fruits.