###### Abstract  
Terpene synthase (TPS) is a critical enzyme responsible for the biosynthesis of terpenes, which possess diverse roles in plant growth and development. Although many terpenes have been reported in orchids, limited information is available regarding the genome-wide identification and characterization of the TPS family in the orchid, _Dendrobium officinal_. By integrating the _D. officinal_ genome and transcriptional data, 34 _TPS_ genes were found in _D. officinal_. These were divided into four subfamilies (TPS-a, TPS-b, TPS-c, and TPS-e/f). Distinct tempospatial expression profiles of _DoTPS_ genes were observed in 10 organs of _D. officinal_. Most _DoTPS_ genes were predominantly expressed in flowers, followed by roots and stems. Expression of the majority of _DoTPS_ genes was enhanced following exposure to cold and osmotic stresses. Recombinant DoTPS10 protein, located in chloroplasts, uniquely converted geranyl diphosphate to linalool in vitro. The _DoTPS10_ gene, which resulted in linalool formation, was highly expressed during all flower developmental stages. Methyl jasmonate significantly up-regulated _DoTPS10_ expression and linalool accumulation. These results simultaneously provide valuable insight into understanding the roles of the TPS family and lay a basis for further studies on the regulation of terpenoid biosynthesis by _DoTPS_ in _D. officinal_. terpene synthase; terpenes; methyl jasmonate; abiotic stress; orchids +
Footnote †: journal: Journal of Molecular Sciences  
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The biosynthetic pathway of volatile terpenes is well characterized in plants (Figure 1). Generally, the C5 precursors DMAPP and IPP are formed, and the direct precursors farnesyl diphosphate (FPP), geranyl diphosphate (GPP), and geranylgeranyl diphosphate (GGPP) are generated. Subsequently, plant terpen are biosynthesized by terpene synthase (TPS), which converts FPP to sesquiterpene in the cytosol via the mevalonic acid (MVA) pathway, and GPP and GGPP to monoterenes and diterpenes, respectively in plastids by the methylerythritol phosphate (MEP) pathway [1,8]. TPS is positioned at the branch point of the isoprenoid pathway, and is a key enzyme for terpenoid synthesis. Each TPS is characterized by two conserved domains, PF03936 (C-terminal) and PF01397 (\(N\)-terminal) [9], as indicated in the Pfam ([[http://pfam.xfam.org/](http://pfam.xfam.org/)]([http://pfam.xfam.org/](http://pfam.xfam.org/))) database. The TPS family is phylogenetically classified into seven subfamilies (TPS-a, TPS-b, TPS-c, TPS-d, TPS-e/f, TPS-g, and TPS-h) [1]. Among them, TPS-a encodes sesquiterpene synthase that is found in both dicotyledonous and monocotyledonous plants. The angiosperm-specific TPS-b encodes monoterpene synthase with a R(R)X\({}_{8}\)W motif that catalyzes the isomerization cyclization reaction. TPS-c is deemed to belong to the ancestral clade and catalyzes copalyl diphosphate synthase. The gymnosperm-specific TPS-d performs several functions, as diterpene, monoterpene, and sesquiterpene synthases. TPS-e/f encodes copalyl diphosphate/kaurene synthases, which are critical enzymes for the production of  
Figure 1: The pathway of terpene synthase genes responsible for the formation of terpenes in planta [3]. Terpenes are biosynthesized by the cytosol mevalonic acid (MVA) and the plastid methylerythritol phosphate (MEP) pathways, the former giving rise to sesquiterpenes and geranyllinalool, and the latter to monoterenes and diterpenes.