Intra-population chemical polymorphism in Thymus pannonicus All. growing in Slovakia.

Solid-phase microextraction technique coupled with gas chromatography-flame ionisation detector and gas chromatography-mass spectrometry was used to investigate the inter- and intra-population chemical polymorphism in volatile constituents of three populations of Thymus pannonicus growing in Slovakia. To have an idea on what really the plant emits under different environmental and physiological conditions, a total of 86 individuals were separately analysed using low extraction temperatures (30°C). Data were analysed using a chemometric approach such as the principal component analysis which revealed a significant intra-population variability with the existence of up to four chemotypes: the most abundant is the p-cymene/γ-terpinene chemotype, followed by the geraniol and linalool chemotypes, and, only in one population, by the γ-muurolene/(E)-caryophyllene chemotype. This differentiation of individual plants inside the populations allows better adaptation to ecological conditions of localities and is probably connected with intrinsic genetic diversity of the species.