## 3 Discussion  
Our findings on the molecular characterization of trichome formation and volatile biosynthesis in _T. sinensis_ are consistent with previous studies in other plants. For instance, similar TPSs have been identified in _Arabidopsis thaliana_ and _Solanum Lyopersicum_, where they play crucial roles in sesquiterpene biosynthesis [23; 36; 39]. However, unlike these species, the GC-MS analysis showed that _T. sinensis_ exhibits unique volatile compound profiles, which may be attributed to the production of specific volatile compounds (such as VSC in Table 1) components; their formation may be the product of the adaptive evolution. Comparative studies of the _TPS_ gene family using a variety of angiosperms have shown that the expansion and functional differences in TPS contribute to the adaptability and diversity of angiosperms and plants, promoting the production of broad-spectrum terpen [40]. Our study not only enhances our understanding of volatile biosynthesis but also provides a potential target for improving the production of valuable compounds in woody vegetables. _T. sinensis_ is widely distributed in China and is an edible vegetable due to its unique flavor. Research has found that it is rich in a variety of compounds with medicinal value, and has been found to contain more than 200 compounds, such as triterpenes, sesquiterpenes,  
Figure 8: Establishment of a transient expression system in _T. sinensis_ seedlings and the detection of volatile substances. (**a**) The high efficiency of the transient expression system in _T. sinensis_ was demonstrated by the pigmentation of the RUBY reporter vector. (**b**) Relative expression of _TsPS1262_ in transgenic _T. sinensis_ leaves. (**c**) The content of sesquiterpene elemene was highly induced in transgenic materials of _T. sinensis_ compared to empty vector control. Three biological replicates are used for statistical analysis. (**d**) The second abundant sesquiterpene \(\gamma\)-elemene was significantly induced. Three biological replicates are used for statistical analysis. * indicates significant changes by _p_-value < 0.05, ** indicates significant changes by _p_-value < 0.01, and *** indicates significant changes by _p_-value < 0.0001.  
diterpenes, sterols, phenols, flavonoidsoids, phenylpropanoids, and other ingredients [41]. The volatile substances of _T. sinensis_ varieties originating from the three regions of Shandong Province, Henan Province, and Anhui Province in China were analyzed by GC-MS, and it was found that the main components are terpenes, thiophenes, and esters [9]. This is similar to our results of measurements using varieties with different trichome densities: both found sesquiterpenes to be the main terpene component (Figure 3e). However, we found that the volatile compounds in the _T. sinensis_ leaves have significant differences among varieties (Figure 3e), suggesting that the synthesis of VOCs is closely related to trichome development. The formation and variation in _T. sinensis_ flavor are the basis of artificial selection, in which the component changes in VOCs are regulated by the synthesis pathway of secondary metabolites. The GC-MS analysis of different varieties of _T. sinensis_ shows that the content of terpenoids (especially sesquiterpenes) and VSCs in VOCs are the main component substances [42]. Studies on the enzyme activities of five sesquiterpene synthases in grapes show that there are significant differences in the final products catalyzed by different TPSs, which indicates the complexity of sesquiterpene components and diverse functions of TPS genes [43]. At present, some progress has been made in the research on the synthesis and regulation of terpenoids in _T. sinensis_. For example, two key terpene synthase genes, _TSTPS1_ and _TsTPS2_, were identified in _T. sinensis_ and found to be specifically expressed in trichomes and regulate the in vitro biosynthesis of (+) limonene and \(\beta\)-elemene, respectively [44].