Comparative Metabolome\nand Transcriptome Analysis\nRevealed the Accumulative Mechanism of Rubusoside in Chinese Sweet\nTea

Terpenoids are important secondary metabolites in <i>Rubus</i>. Rubusoside is a relatively specific diterpenoid bioactive\ncomponent\nin the leaves of Chinese Sweet Tea (Rubus suavissimus). However, the terpenoid anabolic pathway of <i>Rubus</i> and the molecular mechanism underlying the specific accumulation\nof rubusoside in R. suavissimus remain\nunclear. Here, metabolomics and transcriptomics analyses were performed\non differences in terpenoid metabolism levels between R. suavissimus (sweet leaves) and Rubus chingii (bitter leaves). Steviol glycosides\nand goshonosides primarily accumulated in R. suavissimus and R. chingii, respectively. Three\npairs of highly homologous glycosyltransferase genes (<i>UGT85A57</i>, <i>UGT75L20</i>, and <i>UGT75T4</i>) associated\nwith rubusoside biosynthesis in the two <i>Rubus</i> species\nwere identified. The three pairs of UGT proteins in both species could\nglycosylate steviol. Thus, the transcriptional regulation of <i>UGTs</i> in R. suavissimus appears\nto play a pivotal role in rubusoside accumulation. Our findings provide\ninsights into the differences in terpenoid metabolism between R. suavissimus and R. chingii and reveal the molecular mechanism of rubusoside accumulation in R. suavissimus.