Fig. 3

Comparative transcription profiles of the putative genes in the triterpene saponin synthetic pathway in P- and G-type B. vulgaris. a, Heatmaps representing the expression levels of different genes/families determined by RNA-seq. The color bar is shown on the top right. Data represent log (RPKM) of each treatment. The metabolites of the pathway are shown in bright green on top and the enzymes for each metabolic step are shown below in black using the following abbreviations: MVA, mevalonic acid; MEP, 2-C-methyl-D-erythritol 4-phosphate; IPP, isopentenyl diphosphate; G3P, glyceraldehyde 3-phosphate; DMAPP, dimethylallyl diphosphate; GPP, geranyl diphosphate; FPP, farnesyl diphosphate; 2,3-OS, 2,3-oxidosqualene; AACT, acetyl-CoA acyltransferase; HMGS, 3-hydroxy-3-methylglutaryl CoA synthase; HMGR, 3-hydroxy-3-methylglutaryl CoA reductase; MK, mevalonic acid kinase; PMK, phosphomevalonate kinase; MDD, mevalonic acid diphosphate decarboxylase; DXS, deoxy-D-xylulose 5-phosphate synthase; DXR, deoxy-D-xylulose 5-phosphate reductase; MCT, 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase; CMK, 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase; MDS, 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase; HDS, (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP) synthase; HDR, HMB-PP reductase; IDI, IPI isomerase; GPS, geranylgeranyl pyrophosphate synthase; FPS, farnesyl pyrophosphate synthase; SS, squalene synthase; SE, squalene epoxidase; OSC, oxidosqualene cyclases; P450, cytochrome P-450; UGT, UDP-dependent glycosyl transferases. Two stars indicate the two significantly induced genes in P-type plants. b, Q-PCR analysis of three selected genes of the pathway. The ordinates show the relative expression levels; the abscissas show the time points. Error bars indicate the SD of three biological replicates