Identification and Molecular Characterization of Geraniol and Linalool Synthase Genes Related to Monoterpene Biosynthesis in Damask Rose (Rosa damascena Mill.), Several Genes for Little Scent

Rosa damascena Mill. (Damask rose) is a famous traditional flower that is widely appreciated for its valuable essential oil and high-quality fragrance used in the perfume and cosmetics industries. Rose oil contains more than 300 volatile constituents, and the main constituents geraniol, linalool, nerol, and citronellol determine the essential oil quality. In the present study, we reported the cloning and characterization of three rose monoterpene synthase genes related to rose oil quality. The genes encoding geranyl diphosphate synthase (GDPS) designated as RdGDP (accession No. MN650820), geraniol synthase (GES) as RdGES (accession No. MN639696), and linalool synthase (LIS) as RdLIS (accession No. MN639697) and involved in the monoterpene synthases pathways were successfully cloned from R. damascena and their expression profiles in different flower developmental stages were determined by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). The deduced RdGDP, RdGES, and RdLIS proteins contain 383, 603, and 562 amino acids, and the corresponding size of their open-reading frames is 1152, 1812, and 1689 bp, respectively. Expression analysis revealed that these genes demonstrated persistent expressions from the budding to the full opening stages of R. damascena flower development, and the expression levels of RdLIS were lower than that of RdGDP and RdGES. These results suggest that the GDP and GES can regulate the biosynthesis of floral scents in Damask rose flowers. The cloning of rose genes, including RdGDP, RdGES, and RdLIS, could have far-reaching implications for improving the quality of R. damascena essential oils through metabolic engineering.