Integrated Data Reveal the Flavonoid Biosynthesis Metabolic Pathway in Semen Ziziphi Spinosae Using Transcriptomic and Metabolomic

The extract from Semen Ziziphi Spinosae (SZS) contains many secondary metabolites (flavonoids, alkaloids, and terpenoids), widely reported for their high medicinal value. In order to know the number and type of flavonoids and the regulating mechanism of flavonoid biosynthesis during the growth and development of SZS, we identified and analyzed the flavonoid metabolites and genes in SZS using metabolomic and transcriptomic. A total of 13,232 differentially expressed genes and 83 flavonoid metabolites were identified at three different growth and development stages (T1, T2, and T3) of SZS. The main flavonoid metabolic components of SZS were cate-chin, L-epicatechin, (-)-epigallocatechin, (+)-gallocatechin, spinosin and its derivatives. A total of 53 unigenes encoding 15 enzymes were identified as candidate genes involved in flavonoid biosynthesis in SZS. Among, PAL, C4H, 4CL, CHS, CHI, FLS, FNS, ANS, ANR, LAR, and UFGT genes were all downregulated in T3 than in T1. The expression levels of these genes influence the accumulation of flavonoids in SZS. Our results should pro-vide valuable information for flavonoid metabolites and candidate genes involved in flavonoid biosynthesis on SZS