FIGURE 3.

Heatmap representing the expression of potential candidate genes involved in xanthanolide biosynthesis in the trichomes and young leaves of Hubei-cultivar. (A) The precursors IPP and DMAPP for the biosynthesis of xanthanolides were indicated to be from both the MVA and MEP pathways by the analysis of X. strumarium transcriptomes. (B) Transcript abundances of putative pathway genes were compared between the trichomes (HT) and the young leaves (HY). The transcript abundance of genes was calculated by the FPKM method. Red color indicates high expression and green color indicates low expression. Genes encoding all the known enzymes in both the MVA and MEP pathways up to IPP or DMAPP were present in the X. strumarium transcriptome, and the full names of these known enzymes are shown in Supplementary Table 12. In the pathway from IPP or DMAPP to xanthanolides, there were several glandular trichome-specifically expressed unigenes, including two unigenes (CL12450.Contig1_All and CL12450.Contig2_All) encoding farnesyl diphosphate synthase (FDS), one full-length unigene (Unigene16952_All) encoding a germacrene A synthase (XsTPS3), and four full-length unigenes coding for CYP71 members (CYP71AV14, CYP71BL7, CYP71DD1, and CYP71AX30).