Fig. 2

Two parallel pathways of CPT biosynthesis were proposed by metabolite profiling of intermediates in O. pumila. a Metabolites and identified enzymes involved in CPT biosynthesis in O. pumila. LAMT, loganic acid methyltransferase; SLAS, secologanic acid synthase; SLS, secologanin synthase; STR, strictosidine synthase; STRAS, strictosidinic acid synthase. Steps shaded in blue are part of the prestrictosidine pathway, while orange denotespoststrictosidine is the poststrictosidine pathway. b Tissue distribution profiles of proposed CPT pathway metabolites in O. pumila plants and hairy roots (4 replicates). Tissues were collected from wild-type plants grown on Gamborg B5 medium for 3 months, and methanol extracts were analysed using a 38.5-min gradient elution method for mass spectrometry (MS) detection. Multiple isomers were detected for deoxypumiloside, pumiloside, and strictosidine epoxide. Data are shown as the mean ± SD (n = 4) for the most abundant and quantifiable isomers. Hr, hairy root; Rt, root; St, stem; Lf, leaf