Functional characterization of terpene synthases and chemotypic variation in three lavender species of section Stoechas

Abstract

Lavandula pedunculata (Mill.) Cav. subsp. lusitanica, Lavandula stoechas L. subsp. stoechas and Lavandula viridis l'Hér. are three lavender taxa that belong to the botanical section Stoechas and are widely used as aromatherapy, culinary herb or folk medicine in many Mediterranean regions. The analysis of their bioactive volatile constituents revealed the presence of 124 substances, the most abundant being the bicyclic monoterpenes fenchone, camphor and 1,8-cineole that give these three species their respective chemotypes. Most noteworthy was fenchone which, with its reduced form fenchol, made 48% of the total volatile constituents of L. pedunculata while present at 2.9% in L. stoechas and undetectable in L. viridis. In order to provide a molecular explanation to the differences in volatile compounds of these three species, two monoterpene synthases (monoTPS) and one sesquiterpene synthase (sesquiTPS) were cloned in L. pedunculata and functionally characterized as fenchol synthase (LpFENS), α-pinene synthase (LpPINS) and germacrene A synthase (LpGEAS). The two other lavender species contained a single orthologous gene for each of these three classes of TPS with similar enzyme product specificities. Expression profiles of FENS and PINS genes matched the accumulation profile of the enzyme products unlike GEAS. This study provides one of the rare documented cases of chemotype modification during plant speciation via changes in the level of plant TPS gene expression, and not functionality.

Genomic Analysis of Terpene Synthase Family and Functional Characterization of Seven Sesquiterpene Synthases from Citrus sinensis

“…This apparent discrepancy probably arises from the fact that the emitted volatiles do not always coincide with the volatile compounds accumulated in a given plant/tissue, as it has been shown in some plants (Llusia and Peñuelas, 2000 ; Ormen et al, 2011 ). Even more, it can also occur that sesquiterpene synthase genes expression profile and accumulation of the corresponding product in plant tissues do not correlate, as it has been reported for germacrene-A synthase in lavender (Benabdelkader et al, 2015 ). Concretely, citrus terpenes are synthetized and stored in specialized oil glands, and although there are no works reporting comparative volatile emission/content, our unpublished results point that they can greatly differ in some tissues/developmental stages (i.e., while D-limonene contributed <3% to total volatiles emitted from peel of mature fruit it constitutes more than 90% of total volatiles accumulated in this tissue).…”

Germacrene A–A Central Intermediate in Sesquiterpene Biosynthesis

“…Sometimes the absolute configuration can be rationally suggested, because 1 is transformed in the same organism into another compound such as (+ +)-costunolide. [18][19][20][21] Further GASs are known from many other plant species, [22][23][24][25][26][27][28][29][30][31][32] but the absolute configurationo f1 has frequently not been determined. While the accumulated literature shows that (+ +)-1 is typical for plants, the recently characterisedb acterial GAS from Micromonosporam arina produces (À)-1, [33] reflectingt he observationt hat terpenes and cationic intermediates towards them from plants and bacteria often represent differente nantiomers.…”

Terpene profiling, transcriptome analysis and characterization of cis-β-terpineol synthase from Ocimum

“…Using amino acid sequence and protein function, TPSs have been organized into different sub-families, which includes, three angiosperm specific family (TPS-a, TPS-b and TPS-g), a gymnosperm specific subfamily (TPS-d), while TPS-c is most conserved among the land plants; TPS-e and f is conserved among the vascular plants (Bohlmann et al 1998;Chen et al 2011;Benabdelkader et al 2015). Upon sequence analysis of these three contigs, presence of conserved domains and other characteristics of TPS gene family was evident (Fig.…”