# FhMYB108 Regulates the Expression of Linalool Synthase Gene in _Freesia hybrida_ and _Arabidopsis_
## 3 Results
### Relevant Regulatory Molecules of Linalool  
Currently, a total of eight terpene synthase genes (_FhTPS1 FhTPS2 FhTPS3 FhTPS4 FhTPSS FhTPS6 FhTPS7_, and _FhTPSS8_) have been identified in _F. hybrida_[37]. Among them, it has been discovered that _FhTPS1_ exclusively utilizes GPP as a substrate to generate linalool, which potentially serves as the primary source of the volatile compounds in the _F. hybrida_ flowers. To quantify the expression of _FhTPS1_ across diverse developmental stages and floral organs, including petals, pists, petals, receptacles, and stames, our findings revealed a robust expression pattern of _FhTPS1_ in petals, pistils, and stamens; conversely, its expression was significantly lower in sepals and receptacles (Figure 2A). The crucial aspect lies in the striking similarity between its expression level and the release pattern of linalool, which demonstrated a gradual increase that aligns with flower blooming (Figure 2B). This observation strongly suggests that the catalytic activity of FhTPS1 may be solely accountable for linalool in the _F. hybrida_ flowers. Based on previous transcriptome data [3], we identified three full-length cDNA sequences encoding MYB transcription factors in _F. hybrida_, namely _FhMYB21L1_ (591 bp), _FhMYB21L2_ (591 bp), and _FhMYB108_ (789 bp). These sequences were obtained through homologous comparison with the _AtMYB21_ and _AtMYB24_ transcription factors in _A. thaliana_, known for their regulatory role in terpenoid metabolism. The regulatory functions of _FhMYB21L1_ and _FhMYB21L2_ in terpenoid metabolism have been experimentally validated, while the role of _FhMYB108_ remains unreported [38]. The FhMYB108 exhibits two characteristic R2R3-MYB transcription factor domains, renowned for their ability to specifically \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Compounds** & **S1** & **S2** & **S3** & **S4** & **S5** \\ \hline \(\alpha\)-Pinene & n.d & n.d & n.d & 23.58 \(\pm\) 2.16 & 30.87 \(\pm\) 4.52 \\ \(\beta\)-pinene & n.d & n.d & n.d & 40.99 \(\pm\) 4.85 & 24.86 \(\pm\) 3.10 \\ Dehydrocineole & n.d & n.d & n.d & n.d & 20.83 \(\pm\) 1.48 \\ Myrcne & n.d & n.d & n.d & 59.02 \(\pm\) 4.87 & 72.65 \(\pm\) 4.88 \\ \(\alpha\)-Terpinene & n.d & n.d & n.d & 6.89 \(\pm\) 2.01 & 38.15 \(\pm\) 3.75 \\ D-Limonene & n.d & n.d & 15.89 \(\pm\) 4.02 & 42.89 \(\pm\) 4.17 & 155.21 \(\pm\) 8.55 \\ trans-Ocimene & n.d & n.d & 48.56 \(\pm\) 3.41 & 120.36 \(\pm\) 10.25 & 635.1 \(\pm\) 26.55 \\ Cis-ocimene & n.d & n.d & 24.26 \(\pm\) 3.88 & 189.25 \(\pm\) 10.52 & 745.12 \(\pm\) 20.78 \\ cis-Linaloloxide & n.d & n.d & n.d & 70.68 \(\pm\) 7.45 & 147.29 \(\pm\) 18.26 \\ Terpinolene & n.d & n.d & n.d & 8.88 \(\pm\) 6.02 & 46.21 \(\pm\) 5.12 \\ Linalool & n.d & 29.32 \(\pm\) 2.06 & 158.36 \(\pm\) 7.69 & 6845.48 \(\pm\) 204.36 & 17,963.14 \(\pm\) 364.88 \\
4-Terpineol & n.d & n.d & n.d & 24.84 \(\pm\) 2.86 & 34.29 \(\pm\) 5.14 \\ \(\alpha\)-Terpineol & 8.26 \(\pm\) 2.06 & 18.26 \(\pm\) 3.07 & 135.98 \(\pm\) 8.66 & 6889.21 \(\pm\) 59.64 & 8795.66 \(\pm\) 276.11 \\ Cycloisoisativene & n.d & n.d & n.d & 10.25 \(\pm\) 1.87 & 33.26 \(\pm\) 3.55 \\ \(\gamma\)-Gurjunene & n.d & n.d & n.d & 22.02 \(\pm\) 4.20 & 73.58 \(\pm\) 2.55 \\ Nerodilol & n.d & n.d & n.d & 21.55 \(\pm\) 3.47 & 37.98 \(\pm\) 5.64 \\ Dihydro-ionone & n.d & n.d & 3.02 \(\pm\) 2.55 & 588.21 \(\pm\) 60.54 & 908.23 \(\pm\) 40.88 \\ \(\beta\)-Ionone & n.d & n.d & 8.22 \(\pm\) 4.20 & 2701.84 \(\pm\) 105.32 & 4429.14 \(\pm\) 207.44 \\ Ionone & n.d & n.d & n.d & n.d & 65.88 \(\pm\) 6.45 \\ \hline \hline \end{tabular} (The data are represented by means \(\pm\) standard deviations (\(n=3\)). n.d: not detected).  
\end{table} 
Table 2: Release of volatile compounds from _Red River(r)_ flowers at different stages of blooming (ng g\({}^{-1}\) FW). bind to MYB elements (Figure 2C).