Variation of Volatiles in Tunisian Populations of Teucrium polium L. (Lamiaceae)

Volatiles from wild Tunisian diploid (2n=2x=26) and tetraploid (2n=4x=52) Teucrium polium L. populations from five bioclimatic zones were assessed by GC and GC/MS. Thirty‐eight compounds were identified. Main volatiles at the species level were myrcene (6; 15.3%), germacrene D (27; 9.0%), α‐pinene (6.6%), β‐pinene (3; 5.8%), and α‐cadinol (38; 5.1%). A significant variation among populations was observed. The tetraploid populations belonging to the sub humid and lower semi arid bioclimates showed a high amount of myrcene (6; 24.2–43.8%), those from the upper arid contain high percentages of α‐cadinol (38; 50.6%). The dominant compounds in diploid populations, mainly located in the semi arid zone, are α‐pinene (1) and germacrene D (27). Population chemical structure, assessed by a principal component analysis (PCA) using all identified compounds, is concordant with bioclimate and ploidy level. In situ conservation of populations should be made appropriately according to these two factors.