Roses Produce Their Sweet Scent Through An Unexpected Route

Taking the time to stop and smell the roses can help you appreciate the simple beauty of life. Recently, a team of French researchers took the time to uncover how roses produce these sweet odors, and found that the plants do so through an unexpected route. The findings could help rose breeders develop flowers with more powerful scents.

Geraniol, a monoterpene, makes up much of rose oil’s signature scent. In many plants, geraniol synthase, an enzyme that belongs to the terpene synthase family, is responsible for producing the fragrant molecule.

So researchers were surprised to find that, in roses, geraniol biosynthesis is mediated instead by a completely different enzyme. Through genetic mapping analysis, the team found that highly scented roses expressed the gene, RhNUDX1, at greater levels than their less fragrant counterparts (Science 2015, DOI: 10.1126/science.aab0696).

RhNUDX1 codes for a new enzyme in the Nudix hydrolase family. The enzyme cleaves a phosphate group from geranyl diphosphate, a precursor of geraniol. The team thinks that a still undetermined phosphatase then hydrolyzes the resulting compound to produce geraniol.

Utilizing RhNUDX1 as a genetic marker may help rose breeders identify and propagate more sweet-smelling flowers for the flower shop market, says study author Sylvie Baudino. “Many of these flowers have lost scent” because breeders paid attention to other traits, such as color or shelf life, says Virginia Tech ecologist Dorothea Tholl, who cowrote an accompanying commentary to the Science paper.

Tholl also says this unexpected pathway for creating a familiar natural product is an example of biosynthetic plasticity in the plant kingdom. “It is very likely,” she says, “that we will find other examples—maybe related to this Nudix-specific pathway—in other plants.”

Baudino’s group is now looking to see if other plants, such as the rose’s close relative the strawberry, produce geraniol in the same way.