Science 349, 81–83 (2015)

Monoterpenes are the major components in the fragrance of roses and their loss has caused some rose cultivars bred for visual attributes to be odourless. To restore the scent of these roses would require an in-depth understanding of the biosynthetic pathway of monoterpenes. To that end Jean-Louis Magnard and colleagues have identified a Nudix hydrolase, RhNUDX1, responsible for monoterpene biosynthesis and fragrance in roses.

Credit: PHOTODISC/GETTY IMAGES

The researchers examined the differences between the transcriptomes of two rose cultivars: the heavily scented Papa Meilland and Rouge Meilland with only a faint scent. The RhNuDX1 gene exhibited the highest differential expression between the two. Furthermore, RhNUDX1 expression correlated with the quantity of monoterpenes in ten rose cultivars, and its mRNA and protein levels correlated with scent emission throughout petal development. Downregulating RhNUDX1 using RNA interference results in reduced monoterpenes. Further analysis co-localized a major quantitative trait locus with RhNUDX1 which explained 76% of the variation in monoterpene content. Together, these data support the role of RhNUDX1 in monoterpene biosynthesis.

Biochemical assays confirmed the geranyl diphosphate diphosphohydrolase activity of RhNUDX1 in vitro. Using transient expression in tobacco leaves the researchers validated the function of RhNUDX1 in the biosynthesis of geraniol, a monoterpene alcohol, in planta. This may provide a solution for boosting the scent of low-RhNUDX1 roses.