Molecular Phylogeny and Phytochemistry of the Genus Origanum

Origanum (Nepetoideae, Lamiaceae) is a taxonomically complex genus that includes economically important species such as marjoram (Origanum majorana) and oregano (diverse members of the genus) which has been used as aromatic and medicinal plants. The high antimicrobial and antioxidant activity of some Origanum species offers new application fields in food and feed industry and in cosmetics. The intrageneric classification of Origanum is complicated and an issue of debate due to natural hybridisations. In case of Origanum majorana it is not clear if it should be treated as member of the genus or as a distinct genus. The aim of the molecular part of this project is to test the monophyly of the genus and to assess phylogenetic relationships of Origanum species by using DNA sequence data. Besides DNA regions usually sequenced for investigations at lower systematic levels the gene responsible for gamma-terpinene synthase, a key enzyme in the monoterpene biosynthesis, will be of special interest. Sequence information of this gene will be used for phylogenetic analysis of the genus and an intrageneric phylogeny of the gamma-terpinene synthase gene will be created. The plant secondary compounds mainly responsible for the economic use of Origanum species are the mono- and sesquiterpenes (essential oil compounds) which show sensorial and partly antimicrobial and antioxidant properties. Further important compounds are, due to their heigh antioxidant potential, the polyphenols. Arbutin, a hydroquinone derivative which is present in marjoram may be regarded as a compound not desired in food because of its high biological activity. Arbutin is not present in Origanum vulgare, but its presence or absence in other species of the genus is not known. The aim of the phytochemical part of this project is to fill up gaps in knowledge about the essential oil composition of Origanum species. Moreover the variability of polyphenols and antioxidant activity between species and within populations of selected species will be investigated. The occurence of arbutin within the genus will be studied to give advice which species should be avoided when producing oregano.

Origanum (Nepetoideae, Lamiaceae) is a taxonomically complex genus that includes economically important species such as marjoram (Origanum majorana) and oregano (diverse members of the genus) which has been used as aromatic and medicinal plants. The high antimicrobial and antioxidant activity of some Origanum species offers new application fields in food and feed industry and in cosmetics. The intrageneric classification of Origanum is complicated and an issue of debate due to natural hybridisations. In case of Origanum majorana it is not clear if it should be treated as member of the genus or as a distinct genus. The aim of the molecular part of this project is to test the monophyly of the genus and to assess phylogenetic relationships of Origanum species by using DNA sequence data. Besides DNA regions usually sequenced for investigations at lower systematic levels the gene responsible for gamma-terpinene synthase, a key enzyme in the monoterpene biosynthesis, will be of special interest. Sequence information of this gene will be used for phylogenetic analysis of the genus and an intrageneric phylogeny of the gamma-terpinene synthase gene will be created. The plant secondary compounds mainly responsible for the economic use of Origanum species are the mono- and sesquiterpenes (essential oil compounds) which show sensorial and partly antimicrobial and antioxidant properties. Further important compounds are, due to their heigh antioxidant potential, the polyphenols. Arbutin, a hydroquinone derivative which is present in marjoram may be regarded as a compound not desired in food because of its high biological activity. Arbutin is not present in Origanum vulgare, but its presence or absence in other species of the genus is not known. The aim of the phytochemical part of this project is to fill up gaps in knowledge about the essential oil composition of Origanum species. Moreover the variability of polyphenols and antioxidant activity between species and within populations of selected species will be investigated. The occurence of arbutin within the genus will be studied to give advice which species should be avoided when producing oregano.