Molecular and Phytochemical Variability of Common Juniper (Juniperus communis L.) in the Central Balkans Reveals Differentiation of Populations

Juniperus communis is the juniper with the widest geographical distribution, owing to its high ecological valence. Nevertheless, there is only a limited number of studies of its phenotypic and molecular variability. In this study, we coupled leaf essential oil (EO) composition with molecular and environmental data to better understand this species’ distribution and variability in the central Balkans. EOs were obtained by simultaneous hydrodistillation and extraction, and analysed using GC coupled with MS and FID detectors. For molecular analysis, inter-simple sequence repeats (ISSR) using five primers were analysed. Three chemotypes were most abundant in the study area: sabinene, an intermediate chemotype, and α-pinene. Several additional chemotypes were also identified. In total, 118 compounds present above 0.05% were detected and identified. Monoterpene hydrocarbons dominated the EO composition (43.8–79.1%). Multivariate analyses showed separation of populations from north to south. ISSRs yielded 78 polymorphic bands. Three genetic pools could also be identified that roughly correspond to this distribution, though data is not completely congruent with chemophenetic. Results indicate high genetic diversity, with high gene flow between populations, but also certain differentiation of populations.