Rose fragrance: Genomic approaches and metabolic engineering

For centuries, rose (Rosa hybrida) has been the most important crop in the floriculture industry. Rose petals represent a unique system for studies of a wide range of highly important topics, such as the biosynthesis of secondary metabolites, including scent compounds and pigments, as well as developmental processes. Advances in genomics have made it possible to integrate entire genetic programs responsible for key processes, instead of focusing on individual phenomena via reductionist approaches. To this end, we generated cDNA libraries of rose petals to develop ESTs (expressed sequence tags). About 3000 ESTs have already been sequenced and catalogued. DNA chips were prepared and, using microarray analyses, numerous ESTs whose expression coincide with fragrance production were identified. To complement the genomic data, proteomic protocols for rose petals were developed: ca. 1000 proteins were mapped and their expression pattern during petal development characterized. Sequence information on ca. 100 of these proteins was also generated. In parallel, chemical and biological patterns of scent production and emission were determined and characterized by gas chromatography-mass spectrometry in petals of ca. 20 rose varieties. From these combined results, we identified several novel genes with putative function in numerous important processes, including fragrance production. For some of these the function was proven using Escherichia coli expression assay and/or transgenic plants. Furthermore, we have already generated transgenic flowers with either enhanced scent or novel fragrance composition.