Evolution of Terpene Synthases in Orchidaceae

Abstract

Terpenoids are the largest class of plant secondary metabolites and are one of the major emitted volatile compounds released to the atmosphere. They have functions of attracting pollinators or defense function, insecticidal properties, and are even used as pharmaceutical agents. Because of the importance of terpenoids, an increasing number of plants are required to investigate the function and evolution of terpene synthases (TPSs) that are the key enzymes in terpenoids biosynthesis. Orchidacea, containing more than 800 genera and 28,000 species, is one of the largest and most diverse families of flowering plants, and is widely distributed. Here, the diversification of the TPSs evolution in Orchidaceae is revealed. A characterization and phylogeny of TPSs from four different species with whole genome sequences is available. Phylogenetic analysis of orchid TPSs indicates these genes are divided into TPS-a, -b, -e/f, and g subfamilies, and their duplicated copies are increased in derived orchid species compared to that in the early divergence orchid, A. shenzhenica. The large increase of both TPS-a and TPS-b copies can probably be attributed to the pro-duction of different volatile compounds for attracting pollinators or generating chemical defenses in derived orchid lineages; while the duplications of TPS-g and TPS-e/f copies occurred in a species-dependent manner.

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

“…We classified them into three categories: TPS-a, TPS-b, and TPS-e/f. TPS-b was the most expanded category, which was consistent with patterns in D. officinale , V. planifolia , and D. catenatum , and C. faberi have more genes in TPS-b than P. equestris ( Yu et al, 2020 ; Huang et al, 2021 ). However, it was not consistent with A. thaliana , O. sativa , and S. bicolor , which have a dominant subfamily TPS-a ( Aubourg et al, 2002 ; Chen et al, 2011 ).…”

“…Thirty-two CfTPS proteins belonged to three categories according to the phylogenetic tree ( Figure 3 ): TPS-a, TPS-b, and TPS-e/f. Of these three categories, the TPS-a and TPS-b clades contained the most members and were the most expanded categories, with 13 and 15 genes, respectively, and were consistent with other plant species, such as A. thaliana , C. sinensis , V. planifolia , D. catenatum , P. equestris , and D. officinale ( Aubourg et al, 2002 ; Yu et al, 2020 ; Zhou et al, 2020 ; Huang et al, 2021 ). The remaining four TPS genes belonged to the TPS-e/f subfamily.…”

“…Terpenoids are predominant components in orchid flower volatiles, but genome-wide TPS identification is limited in orchids ( Ramya et al, 2018 ; Yu et al, 2020 ). Orchidaceae comprises five subfamilies, and in recent reports, a few TPS genes have been identified in Apostasia shenzhenica in Apostasioideae subfamily; Vanilla planifolia in Vanilloideae subfamily; and Phalaenopsis equestris and Dendrobium catenatum in Epidendroideae subfamily ( Huang et al, 2021 ). However, genome-wide TPS genes identification in Orchidoideae was limited.…”

An Update on the Function, Biosynthesis and Regulation of Floral Volatile Terpenoids

“…Plant TPS genes are widely distributed in flower tissues including buds, pistils, petals, stamens, tubes, corollas, sepals, stigmas and pollen [36,181]. Approximately 1000 monoterpenes and more than 7000 sesquiterpenes have been reported [182]. To date, more than 2000 TPS genes are responsible for the biosynthesis of monoterpenes, while sesquiterpenes have been identified in more than 40 species [182,183].…”

“…Approximately 1000 monoterpenes and more than 7000 sesquiterpenes have been reported [182]. To date, more than 2000 TPS genes are responsible for the biosynthesis of monoterpenes, while sesquiterpenes have been identified in more than 40 species [182,183]. Table 1 lists some of the TPS genes that have been identified in flowering plants recently.…”