DNA Barcoding of St. John's wort (Hypericum spp.) Growing Wild in North-Eastern Greece

Plants of the genus Hypericum, commonly known as "St. John's wort" ("spathohorto" or "valsamo" in Greek), have been used since antiquity for their therapeutic properties. Wild-harvested Hypericum plants are still popular today in herbal medicines, commercially exploited due to their bioactive compounds, hypericin and hyperforin, which have antidepressant, antimicrobial and antiviral activity. Species identification of commercial products is therefore important and DNA barcoding, a molecular method that uses small sequences of organisms' genome as barcodes, can be useful in this direction. In this study, we collected plants of the genus Hypericum that grow wild in North-Eastern Greece and explored the efficiency of matK, and trnH-psbA regions as DNA barcodes for their identification. We focused on 5 taxa, namely H. aucheri, H. montbretii, H. olympicum, H. perforatum subsp. perforatum, and H. thasium, the latter a rare Balkan endemic species collected for the first time from mainland Greece. matK (using the genus-specific primers designed herein), trnH-psbA, and their combination were effectively used for the identification of the 5 Hypericum taxa and the discrimination of different H. perforatum subsp. perforatum populations. These barcodes were also able to discriminate Greek populations of H. perforatum, H. aucheri, H. montbretii, and H. olympicum from populations of the same species growing in other countries.