## 3 Discussion
Phylogenomic synteny network analysis has been performed to examine the MADS-box, LEA (Late Embryogenesis Abundant), and MYB (v-myb avian myeloblastosis viral) gene families. Such analysis could be used to reveal genomic diversification, positional conservation, ancient tandem duplications, and lineage-specific transpositions [54; 55; 56]. However, this method did not appear to be so effective for analyzing the TPS gene family. First, among the 3802 TPSs of 115 angiosperms, only 1618s TPS were found to have syntenic relationships; this quantity is quite low. Second, in our syntenic cluster analysis, unlike the MADS-box and MYB gene families, many TPS edges could not be separated, and these edges were mixed and interwoven to form the huge syntnet cluster126 (Tables S4 and S5). These features point to the complexity of TPS evolution. These TPSs without syntenic genes in other species represent \"specialized gifts\" prepared by angiosperms on their respective evolutionary journeys. The ancestral TPS originated in land plants after their divergence from green algae and encoded a bifunctional copalyl/kaurene synthase (CPSK) [8]. The TPS-c subgroup contains extant examples of bifunctional CPSKS, which are functionally analogous to the ancestral TPS required for the biosynthesis of gibberellins and related phytohormones [19; 57]. As shown in Figure 2C, the syntenic relationships of TPS-c subfamily members are tightly connected. Moreover, phylogenetic analysis (Figure 3) indicated a high degree of conservation among TPS-c subfamily members in angiosperms. The TPS-e/f subgroup includes kaurene synthase genes, which are required for phytohormone biosynthesis. TPS-f is thought to be derived from TPS-e [22]. As shown in Figure 3, the TPS-e branch separated into two clades. These findings suggest that new functional domains may have appeared in the TPS-e subgroup of angiosperms. Investigating TPSs is important for understanding the evolution of terpenoid biosynthesis in plants. Here, except for the important diterpenes (such as gibberellins and membrane sterols), we mainly focused on volatile monoterenes and sesquiterpenes involved in floral scents. Rose is a great model in which to explore fragrance. We conducted a comprehensive analysis of the TPS gene family of _R. chinensis_ (Figures 4 and 5). Our data indicate that the expansion of TPS-a in _R. chinensis_ mainly occurred via tandem duplication, and only one TPS-a subfamily member (RchiOBHmChr5g0037011) shares syntenic relationships with members in other angiosperms. The functions of the expanded TPS-a subfamily in rose (the types and contents of sesquiterpenes might also have expanded) are being intensively studied. While transcriptomic data suggest diverse expression patterns across RcTPS paralogs, our focused analysis of RcTPS23 demonstrates how phylogenomic synteny can prioritize candidates for functional studies. Systematic validation of additional TPSs remains an important direction for future research. If non-syntenic TPSs expand, they may confer new terpene synthesis activities in plants. Analyzing TPSs with syntenic relationships might also shed light on the conservation of TPS function. Most terpen are classified as secondary metabolites that help plants better adapt in their local environments [58]. Recent studies further elucidate TPS-mediated defense mechanisms across diverse species: In maize, ZmTPS12-produced dolabralexins confer resistance against _Fusarium graminearum_ through direct antifungal activity [59]. Dendrobium orchids upregulate DcTPS7 expression under herbivore attack, catalyzing germacrene D synthesis to repel insects [60]. Potato SttPS2 synthesizes bulnesol/elemol diterpenes that systemically prime jasmonate signaling upon wounding [61]. Notably, tea plant CsTPS1 and CsTPS2 produce defense-related sesquiterpenes (\(\delta\)-cadinene and \(\alpha\)-humulene) that synergistically enhance resistance to _Ectropis obliqua_[62]. These findingscollectively highlight the evolutionary convergence of TPS diversification in biotic stress adaptation.