Status of medicinal and aromatic plants in - Inia

PRESENTED PAPERS 147
Genetic variability of native populations of oregano in Slovenia
Jelka Šuštar-Vozlič
Agricultural Institute of Slovenia, Ljubljana, Slovenia
Introduction
Many species belonging to the Origanum genus, rich in essential oils, phenolic compounds
and flavonoids, have been used for thousands of years as spices and in traditional medicine.
Nowadays, a number of other properties are reported as well (e.g. antifungal, antibacterial,
antioxidant, antiviral, nematicidal). The taxonomy of the genus Origanum is rather
complicated and is still a current issue of debate. The genus is characterized by large
differences in morphological and chemical properties resulting in the distinction of 49 taxa
and 43 species as well as 18 hybrids (Kintzios 2002). The most comprehensive revision of the
genus was done by Ietswaart (1980), who divided the taxa in ten sections, the monospecific
section Origanum being the most widely distributed.
In Slovenia, O. vulgare subsp. vulgare occurs wild in nature and autochthonous
populations differ largely in their morphological as well as biochemical characteristics
(Baričevič 1997). They are characterized by a low content of essential oils (up to 0.5%);
nevertheless they show a considerable antioxidant activity. Large variability in the
morphological as well as in the biochemical properties could be a reflection of either
environmental differences, a product of microclimatic variations found in Slovenia, or of
genetic differences between the populations and clones, or a combination of both factors.
Classical methods of estimating genetic diversity among groups of plants have relied
upon morphological or chemical characters, but these characters can be influenced by
environmental factors. By looking directly at the genetic material itself, molecular markers
represent a powerful and potentially rapid method for the characterization of diversity per se
within the in situ and ex situ conservation (Ford-Lloyd 2001). However, molecular studies
dealing with medicinal and aromatic plants (MAPs) are rare in comparison with other
cultivated plants. This is probably due to the presence of large amounts of secondary
metabolites and essential oils in MAP tissues, which inhibit DNA amplification in PCR
reaction (Khanuja et al. 1999; Mizukami and Okabe 1999). There have been only two
molecular studies on the genus Origanum reported until now. A molecular systematic study
of the family Lamiaceae using rbcL gene sequences was made by Kaufamnn and Wink (1994)
with two Origanum species (O. vulgare and O. laevigatum) and Majorana hortensis, among
others. Some authors have treated M. hortensis as a member of the Origanum genus, but the
results of this study show that it differs significantly from the two Origanum species and was
therefore suggested to be a separate species. A study using RAPD markers for the
comparison of essential oils and genetic relationship of Origanum x intercedens with its
parental taxa in the island of Crete was performed (Gounaris et al. 2002).
The aim of the present study was to develop a protocol for DNA isolation and to optimize
the PCR reactions for further evaluation of genetic diversity of wild oregano in Slovenia
using RAPD markers.
Materials and methods
Nine populations of O. vulgare subsp. vulgare from Slovenia conserved in the Slovene
national genebank for medicinal and aromatic plants were included in the study. One
population of O. vulgare subsp. hirtum and one population of O. vulgare subsp. vulgare
obtained from the genebank in Georgia were selected as outgroups. The number of plants
tested per population varied from two to five. The list of accessions included in the study is
presented in Table 1.