Molecular genetic diversity in the Origanum genus: EST-SSR and SRAP marker analyses of the 22 species in eight sections that naturally occur in Turkey

Origanum (L.) is a genus of herbaceous perennials with culinary and medicinal uses with many species found in the Mediterranean region. The taxonomic classification of species belonging to this genus has been studied using morphological, biochemical and genetic diversity analyses. In this study, the genetic diversity of 22 Turkish Origanum species (including 24 taxa from eight sections) was examined with 46 herbarium specimens from the Mediterranean, Eastern Anatolian, Central Anatolian, and Black Sea regions of Turkey. Molecular marker data were generated from 25 SRAP primer pairs and six EST-SSR primers which produced 325 alleles. Dendrogram, principal coordinate and population structure analyses revealed the relationships among Origanum sections, species and individuals. Gene flow (PhiPT and Nm) was also studied for a deeper understanding of the relationships and hybridization patterns between sections and species. Molecular separation of the Origanums roughly corresponded to the taxonomy that Ietswaart proposed in 1980 but also suggested that hybridization among sections and species may result in convergence and/or divergence of different sections and species.