**Genome-Wide Identification and Expression Profile of** *TPS* **Gene Family in** *Dendrobium o*ffi*cinale* **and the Role of** *DoTPS10* **in Linalool Biosynthesis**

**Zhenming Yu 1,2,**† **, Conghui Zhao 1,3,**† **, Guihua Zhang <sup>1</sup> , Jaime A. Teixeira da Silva <sup>4</sup> and Jun Duan 1,2,\***


Received: 25 June 2020; Accepted: 28 July 2020; Published: 30 July 2020

**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 o*ffi*cinale*. By integrating the *D. o*ffi*cinale* genome and transcriptional data, 34 *TPS* genes were found in *D. o*ffi*cinale*. 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. o*ffi*cinale*. 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. o*ffi*cinale*.

**Keywords:** terpene synthase; terpenes; methyl jasmonate; abiotic stress; orchids
