Genome-Wide Identification and Expression Profile of TPS Gene Family in Dendrobium officinale and the Role of DoTPS10 in Linalool Biosynthesis

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 officinale. By integrating the D. officinale genome and transcriptional data, 34 TPS genes were found in D. officinale. 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. officinale. 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. officinale.

Evolution of Terpene Synthases in Orchidaceae

“…Most of the orchid TPSs belong to TPS-a and TPS-b subfamilies (89/115, Table 1). In the TPS-a subfamily, copies from dicot and monocot species formed distinct subgroups, which is in accordance to previous studies [15,16]. However, compared to angiosperm dicot species, which have more TPSs in TPS-a subfamily, orchid (monocot) TPSs have more members in TPS-b subfamily than in TPS-a subfamily.…”

“…TPSs in P. equestris and D. officinale have been reported [15,60]. These TPSs are divided into four subfamilies (TPS-a, TPS-b, TPS-c, and TPS-e/f ).…”

“…Terepene synthases (TPSs) are key enzymes in terpenoids biosynthesis. To date, TPSs have been studied in several typical plant genomes, such as Arabidopsis thaliana (Arabidopsis, 32 TPSs) [6], Physcomitrella patens (earthmoss, 1 TPS) [7], Sorghum bicolor (Sorghum, 24 TPSs) [8], Vitis vinifera (grape, 69 TPSs) [9], Solanum lycopersicum (tomato, 29 TPSs) [10], Selaginella moellendorffii (spikemoss, 14 TPSs) [11], Glycine max (soybean, 23 TPSs) [12] Populus trichocarpa (poplar tree, 38 TPSs) [13], Oryza sativa (rice, 32 TPSs) [14], and Dendrobium officinale (Dendrobium orchid, 34 TPSs) [15]. According to the classification principle, TPSs can be generally classified into seven clades or subfamilies: TPS-a, TPS-b, TPS-c, TPS-d, TPS-e/f, TPS-g, and TPS-h [16].…”

Combined Analysis of Volatile Terpenoid Metabolism and Transcriptome Reveals Transcription Factors Related to Terpene Synthase in Two Cultivars of Dendrobium officinale Flowers

“…To further clarify TPS genes’s potential roles in the turquoise module and the blue module, we generated a phylogenetic tree by neighbor-joining method ( Yu et al, 2020 ). Figure 8 showed that DoTPSs proteins were classified into four different clades, 14 in TPS-a, 16 in TPS-b, 3 in TPS-c, and 1 in TPS-e/f.…”

“…Previous studies have identified 34 TPS genes in D. officinale . They were classified into four subfamilies (TPS-a, TPS-b, TPS-c, and TPS-e/f) ( Yu et al, 2020 ). In the experiment, the volatile terpenoids in flowers were identified and quantitatively analyzed for two cultivars of Wanhu No.5 and Wanhu No.6 of D. officinale .…”