Volatile Constituents in the Scent of Roses

The cultivation of roses as an ornamental plant has a long history. Apart from floricultural purposes, roses also have an economic importance as a source of natural fragrance in perfume and cosmetic industry and for medical applications. Rose hips, flowers, and their extracts are used for tea infusions and for flavouring of a broad variety of foods. In the scent of roses, more than 400 volatiles have been identified and this review focuses on the key classes of these compounds. There are several possibilities to classify rose volatile compounds, for example by their biosynthetic pathways or their chemical structures. Beginning with cellular compartmentalization, we summarize the recent findings of volatiles derived from the methylerythritol phosphateand mevalonic acid pathways, the shikimate pathway, and the formation of fatty acid and carotenoid derived volatiles. Additionally, we review recent knowledge about the enzymes involved in these pathways, i.e. methyltransferases, decarboxylases, reductases, carotenoid cleavage enzymes, and -glycosidases. In the light of recent findings, we also summarize the rhythmic release of volatile compounds. Finally, the evolution of scent metabolic pathways of roses and future research aspects are discussed. _____________________________________________________________________________________________________________