Genome-Wide Identification and Expression Analysis of Terpene Synthase Genes in Cymbidium faberi

Qian-Qian Wang; Meng-Jia Zhu; Xia Yu; Yuan-Yang Bi; Zhuang Zhou; Ming-Kun Chen; Jiating Chen; Diyang Zhang; Ye Ai; Zhong-Jian Liu; Siren Lan

doi:10.3389/fpls.2021.751853

Genome-Wide Identification and Expression Analysis of Terpene Synthase Genes in Cymbidium faberi

Front Plant Sci. 2021 Nov 25:12:751853. doi: 10.3389/fpls.2021.751853. eCollection 2021.

Authors

Qian-Qian Wang¹, Meng-Jia Zhu², Xia Yu¹, Yuan-Yang Bi¹, Zhuang Zhou^{1

3}, Ming-Kun Chen¹, Jiating Chen¹, Diyang Zhang¹, Ye Ai¹, Zhong-Jian Liu^{1

3

4}, Siren Lan^{1

2}

Affiliations

¹ Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China.
² College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China.
³ Zhejiang Institute of Subtropical Crops, Zhejiang Academy of Agricultural Sciences, Wenzhou, China.
⁴ Institute of Vegetable and Flowers, Shandong Academy of Agricultural Sciences, Jinan, China.

Abstract

Terpene synthases (TPSs) are essential for forming terpenes, which play numerous functional roles in attracting pollinators, defending plants, and moderating the interaction between plants. TPSs have been reported in some orchids, but genome-wide identification of terpenes in Cymbidium faberi is still lacking. In this study, 32 putative TPS genes were classified in C. faberi and divided into three subfamilies (TPS-a, TPS-b, and TPS-e/f). Motif and gene structure analysis revealed that most CfTPS genes had the conserved aspartate-rich DDxxD motif. TPS genes in the TPS-a and TPS-b subfamilies had variations in the RRX₈W motif. Most cis-elements of CfTPS genes were found in the phytohormone responsiveness category, and MYC contained most of the numbers associated with MeJA responsiveness. The Ka/Ks ratios of 12/13 CfTPS gene pairs were less than one, indicated that most CfTPS genes have undergone negative selection. The tissue-specific expression patterns showed that 28 genes were expressed in at least one tissue in C. faberi, and TPS genes were most highly expressed in flowers, followed by leaves and pseudobulbs. In addition, four CfTPS genes were selected for the real-time reverse transcription quantitative PCR (RT-qPCR) experiment. The results revealed that CfTPS12, CfTPS18, CfTPS23, and CfTPS28 were mainly expressed in the full flowering stage. CfTPS18 could convert GPP to β-myrcene, geraniol, and α-pinene in vitro. These findings of CfTPS genes of C. faberi may provide valuable information for further studies on TPSs in orchids.

Keywords: Cymbidium; expression analysis; floral scent; orchids; terpene synthase; terpenes.