Diversity of the terpene synthesis in the Thuja species – A comparative chemotaxonomic study

Abstract

Significant within-plant variability in the terpene composition of cypress species growing in the Czech Republic has been demonstrated. In Thuja plicata, α-thujone (44.8%) dominates in the leaves, α-pinene (39.3%) dominates in the tree trunks, and β-phellandrene (50.1%) dominates in the female cones. In Thuja occidentalis, beyerene (38.4%) dominates in the leaves, α-pinene (64.9%) in the tree trunks, and β-phellandrene (25.5%) in the female cones. In the case of Platycladus orientalis, α-pinene (37.6%–69.6%) dominates both in the leaves and in the female cones, and cedrol (34.1%) dominates in the tree trunks. As regards the terpene profiles, in the tree trunks, T. plicata and T. occidentalis show a slight proximity due to their similar content of α-pinene and totarol, on the other hand, in the female cones, all three studied species show a slight proximity due to their similar content of β-phellandrene. A significant seasonal trend is proven in the β-phellandrene, limonene, rimuene, α-pinene, β-pinene, and beyerene production in T. plicata leaves. The results of terpene profiles from the leaves have been compared with the available literature data using Principle Component Analysis. It can be stated that, with slight variations, the synthesis of the key terpenes among T. plicata populations is quite uniform. In T. occidentalis populations, too, the biosynthesis of key terpenes is uniform, except in the case of T. occidentalis growing in the Czech Republic. Among P. orientalis populations, the synthesis of key terpene α-pinene is very variable. Although there is strong genetic control, also the Δ-3-carene content is not stable among populations.