Identification, Functional Characterization, and Seasonal Expression Patterns of Five Sesquiterpene Synthases in Liquidambar formosana

Abstract

Terpenoids are a large group of important secondary metabolites that are involved in a variety of physiological mechanisms, and many are used commercially in the cosmetics and pharmaceutical industries. During the past decade, the topic of seasonal variation in terpenoid biosynthesis has garnered increasing attention. Formosan sweet gum ( Liquidambar formosana Hance) is a deciduous tree species. The expression of terpene synthase and accumulation of terpenoids in leaves may vary in different seasons. Here, four sesquiterpene synthases (i.e., LfTPS01, LfTPS02, LfTPS03, and LfTPS04) and a bifunctional mono/sesquiterpene synthase ( LfTPS05) were identified from Formosan sweet gum. The gene expression of LfTPS01, LfTPS02, and LfTPS03 showed seasonal diversification, and, in addition, expression of LfTPS04 and LfTPS05 was induced by methyl jasmonate treatment. The major products LfTPS01, LfTPS02, LfTPS04, and LfTPS05 are hedycaryol, α-selinene, trans-β-caryophyllene, α-copaene/δ-cadinene, and nerolidol/linalool, respectively. The data indicated that the sesquiterpenoid content in the essential oil of Formosan sweet gum leaves shows seasonal differences that were correlated to the sesquiterpene synthase gene expression.

Functional characterization of a defense‐responsive bulnesol/elemol synthase from potato

“…These results clearly indicated a possible conversion between elemol and bulnesol (Figs 4 and S10). Similar to our results L. formosana (LfTPS1) sesquiterpene synthase produces elemol and guaiol as products, which showed lower and higher abundance when injected at 150°C and vice versa at 250°C (Chuang et al 2018). Unlike detection of trace amounts of hedycaryol in StBUS/ELS enzymatic products at 200 and 275°C, there was no hedycaryol in the product profile of LfTPS1 in any of the injection temperatures (Chuang et al 2018).…”

“…Moreover, hedycaryol was not detected at 150 C but a trace amount was detected at 200 and 275 C. These results clearly indicated a possible conversion between elemol and bulnesol (Figs 4 and S10). Similar to our results L. formosana (LfTPS1) sesquiterpene synthase produces elemol and guaiol as products, which showed lower and higher abundance when injected at 150 C and vice versa at 250 C (Chuang et al 2018). Unlike detection of trace amounts of hedycaryol in Fig.…”

“…StBUS/ELS enzymatic products at 200 and 275 C, there was no hedycaryol in the product profile of LfTPS1 in any of the injection temperatures (Chuang et al 2018). The results obtained from biochemical characterization of the recombinant StBUS/ELS was also validated by transient overexpression of StBUS/ELS in potato leaf.…”

“…The predominant product peak (peak 1) of StBUS/ELS was elemol (80%). Previous studies have reported that hedycaryol can undergo thermal rearrangement to form elemol (Jones and Sutherland 1968, Southwell 1970, Jones et al 2011, Koo and Gang 2012, Irmisch et al 2014, Hattan et al 2016, Chuang et al 2018, Liang et al 2018). Elemol was reported to be a thermal rearrangement product from hedycaryol in Hedycarya angustifolia and Phebalium ozothamnoides essential oil (Jones and Sutherland 1968, Southwell 1970).…”

“…Similar to our results, ginger sesquiterpene synthase ST02B produced α‐elemol (44.3%) as the major product using FPP, but hedycaryol was not detected in the GC–MS profiles at a lower temperature (Koo and Gang 2012). Also, Liquidambar formosana sesquiterpene synthase (LfTPS1) was shown to produce β‐elemol as the major product and when analyzed at lower temperatures, precursor hedycaryol was not found (Chuang et al 2018). Moreover, our analysis of StBUS/ELS products at different temperatures indicated a relationship between elemol and bulnesol concentration.…”