## 3 Results
### Terpene Backbone Pathway and Terpene Synthase Expression Patterns in C. keiskei  
A comparative transcriptome profiling of the C. _keiskei_ terpene backbone pathway revealed the presence of essential enzymes involved in the MVA and MEP pathways. In the MVA pathway, the _ACAT_ key component, which has five paralogous copies, was upregulated in a tissue-specific manner (Figure 5). The _HMG synthase1_ (_HMGSI_) gene showed upregulation in the leaf and flower, while _HMGSI2_ was upregulated in the root. One copy of _HMGR_ was upregulated in the flower but downregulated in the leaf and root of _C. keiskei_. (Figure 5). In the MEP pathway, the _DXS_ gene was highly upregulated in the flower but downregulated in the leaf and root. Two copies of the _DXR_ unigene were upregulated in the flower and leaf but downregulated in the root (Figure 5). Four copies of _HDS_ and one copy of _HDR_ were upregulated in both the leaf and flower but downregulated in the root tissue. The _ISFD_ or _IDI_ gene showed upregulation in the leaf and root but not in the flower of _C. keiskei_. The _TPS_ by-production genes _GGPP_ and _FFPP_, which lead to the production of various types of _TPS_, were found in one and two copies, respectively. The _FFPP1_ and _FFPP2_ in the MVA pathway were upregulated in the leaf and flower but downregulated in the root tissue. In contrast, the _GGPP_ unigene was upregulated in the flower and downregulated in the root and leaf of _C. keiskei_ (Figure 5).  
A comparative analysis of _TPS_ expression patterns among the leaf, flower and root of _C. keiskei_ showed that the flower and root had a higher distribution of _TPS_ genes, while fewer _ckTPS_ genes were found in the leaf (Figure 6A). The expression pattern among the samples did not produce a DE value; therefore, the expected count versus _FPKM_ of _TPS_ unigenes from the RSEM analysis was examined. The flower exhibited higher expression  
Figure 5: The expression profile of genes in the MVA/MEP (terpenoid backbone) pathway in C. _keiskei_. HMGS: Hydrooxymethylgluturyl–CoA synthase; _HMGR_: Hydrooxymethylgluturyl–CoA reductase isomerase; _ACAT_: Acetyl–CoA C-acetyltransferase; _DXS_: 1–deoxy–D–xylulose–5–phosphate synthase; _DXR_: 1–deoxy–D–xylulose–5–phosphate reductase isomerase; _ISPD_ and _ISPF_: 2–C–methyl–D–erythhriodal 4–phosphate cytidyltransferase; _CDPMEX_: 4–(Cytidine–5–diphospho)–2–C–methyl–D–erythhriodal kinase; _HDS_: 4–hydroxy–3-methylbut–2–enyl diphosphate synthase; _HDR_: 4–hydroxy–3–methylbut–2–enyl diphosphate reductase; _GGPP_: Geranylgeranyl pyrophosphate synthase; _FFPP_: farnesyl pyrophosphate.  
of the top eight _ckTPS_ genes, with significant FPKM values. The leaf showed the highest FPKM values for six _ckTPS_ genes, and the root showed significant expression values for two _ckTPS_ (Figure 6A).  
A Venn diagram plot showed the common sharing of TPS genes among _C. keiskei_, with 17 _ckTPS_ genes distributed among 28 unique _ckTPS_ (Figure 6B). Six _ckTPS_ genes were shared between the flower and root, and two _ckTPS_ genes were unique to the flower and leaf. One unique _ckTPS_ gene was found in the leaf and root (Figure 6B). However, most of the flower _ckTPS_ genes showed a more significant expression compared to the flower and root. While the root had the highest number of _ckTPS_ genes, their expected count was lower than that in the flower (Figure 6). Overall, this study revealed unique and significantly expressed _ckTPS_ genes in the flower compared to the leaf and root of _C. keiskei_. The expression patterns of 15 _TPS_ unigenes, which had complete ORFs, were examined and compared among the leaf, flower, and root of _C. keiskei_ (Supplementary Figure S9). When comparing the leaf and flower, most of the _ckTPS_ genes were downregulated, and only four _TPS_ genes were upregulated in the _C. keiskei_ leaf. Four unique _TPS_ genes were upregulated when comparing the leaf and root. The majority (nine _ckTPS_ genes) of the upregulated genes were observed in the flower and root of _C. keiskei_ (Supplementary Figure S9).