## 4 Discussion
Transcription factors (TFs) are integral to the regulatory mechanisms governing gene expression, as they recognize and bind to cis-acting elements. In response to adverse environmental conditions, specific transcription factors become activated and interact with cis-acting elements located in the promoter region of stress-related genes, thereby facilitating their expression [36]. In the promoter of _DcTPSb1_, various cis-acting elements associated with different biological roles were identified, with a notable prevalence of elements linked to light responsiveness and MeJA signaling. MeJA is known to enhance the expression of TPS genes, which in turn increase the production of monoterene volatiles. Consequently, MeJA treatment is likely to induce the expression of _DcTPSb1_, as the G-box is present in its promoter. This expression is modulated through interactions between G-box and CGTCA or MYC motifs in the MeJA signal transduction pathway [37], as well as through interactions with transcription factors such as OsMYC2 in rice or TcbZIP60 in _Tanacentum cierarifolium_[38; 39]. Additionally, light conditions may serve as either stimulants or inhibitors, impacting the expression of _DcTPSb1_. The temporal and spatial specificity of terpene emission and expression patterns of TPS genes in higher plants have been well documented [40; 41]. For instance, in _P. bellina_, the specific expression of _PbGDPS_, which is involved in the synthesis of geraniol and linalool, is predominantly observed in flowers, with peak expression occurring after four days of flowering [42]. The expression levels of the _LIS1_ gene (monoterpenoid synthase producing linalool after translation) in the petals of _Osmanthus fragrans_ D'angui' are positively correlated with the release of linalool [43]. Notably, the release of monoterenes is found to occur mainly at the onset of anesthesia in three species belonging to the genus Maxillaria, and family _Maxillariumae_, and the site of production is sepal [44]. In the case of _D. chrysotoxum_, the expression of _DcTPSb1_ is significantly higher in flowers, particularly during the flowering stage, in comparison to leaves, stems, and roots, indicating a stringent regulation of terpenoid production. While volatile compound biosynthesis and emission are typically developmentally regulated, with peak expression in early developmental stages like young leaves, unfertilized flowers, and unripe fruits [45], in _D. chrysotoxum_, the expression of _DcTPSb1_ escalates continuously from the budding stage, reaching its highest levels at the peak of flowering. This observation may suggest that GPP accumulates substantially in fully boom flowers, leading to the production of abundant terpenoid compounds that are subsequently released. Moreover, environmental factors such as light, temperature, and circadian rhythm are known to influence volatile aroma emissions [11, 46], though this inference requires further investigation. DcTPSb1 was characterized as a multi-product terpene synthase associated with the synthesis of a monoterpene, linalool, ocimene, and (-)-alpha-Terpineol, like other multi-product enzymes, such as ThUPS4, ThUPS6, and ThUPS7 found in _Freesia x hybrida_[47]. In contrast, it differs from DoTPS10, DoGES1, and CmTPS2, which encodes a single product in _Dendobium officinal_ and _Clivia miniata_[15, 16, 17, 48]. However, these three products are completely different from the seven aromatic monoterrenes involved in the transcriptional metabolic network. This phenomenon is consistent with our research on DITPSb1/DITPSb2 proteins in _D. loddigesii_[4], and their catalytic products are not related terpen in their transcriptional metabolic network. The transcriptional metabolic regulatory network predicts the regulatory role between genes, transcription factors, and terpene compounds. But it may not necessarily mean that there is a direct regulatory relationship between these three.