The scent of a rose fades over time, and has for hundreds of years.

For centuries, generations of breeding in the quest for longer blooms and petals in shades of nearly every hue have dulled the sweetest smells that once perfumed gardens around the world.

French researchers have now figured out precisely which genes make a rose smell so sweet, and where to tinker in the genome to enhance its distinctive scent.

Although the rose genome has been mapped before, a newly published version is far more complete, indicating which genes tend to travel together — scent and color, for instance — and which genes are responsible for continuous blooming, among other traits.