For centuries, roses have been treasured for their therapeutic, cosmetic, and ornamental qualities. Among its many qualities, flower fragrance holds significant economic value. Over 400 volatile compounds contribute to the complex aroma of roses, with terpenoids, phenylpropanoids, and benzenoids playing dominant roles. Among these, geraniol, a monoterpene, contributes notably to the signature scent of rose oil. However, the fragrance of modern roses has gradually diminished as breeders have focused on enhancing other traits like appearance, adaptation, durability, and vase life. To gain a better molecular understanding of specialized metabolic pathways related to floral scent in roses we carried out QTL studies in the SWxBE autotetraploid rose population [Rosa L. ‘ORAfantanov’ (Stormy Weather™) x Rosa L. ‘Radbrite’ (Brite Eyes™)]. Our study suggests that the QTL for the fragrance was identified on chromosome 2 which colocalized with the genes involved with fragrance such as ODO1, EOBIII, and NUDIX. Two rose genotypes from the SWxBE population, ‘16401-N055’ (slightly fragrant) and ‘16089-N051’ (highly fragrant), were used for transcriptomic analysis. Gene expression analysis suggests that the monoterpenoid pathway was highly active in the highly fragrant rose with the NUDIX gene being highly expressed. Thus, NUDIX, a gene involved in geraniol biosynthesis, is a strong candidate gene for the QTL on chromosome 2. This study lays the groundwork for further exploration of the molecular pathways responsible for the scent of roses.
