Evolution of terpene synthases in orchidaceae

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 pollina-tors or defense function, insecticidal properties, and are even used as pharmaceutical agents. Be-cause 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 bio-synthesis. 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. shen-zhenica. The large increase of both TPS‐a and TPS‐b copies can probably be attributed to the production 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.