Biochemistry and genetics of floral scent: a historical perspective

Floral scent plays a crucial role in the reproductive process of many plants. Humans have been fascinated by floral scents throughout history, and have transported and traded floral scent products for which they have found multiple uses, such as in food additives, hygiene and perfume products, and medicines. Yet the scientific study of how plants synthesize floral scent compounds began later than studies on most other major plant metabolites, and the first report of the characterization of an enzyme responsible for the synthesis of a floral scent compound, namely linalool in Clarkia breweri, a California annual, appeared in 1994. In the almost 30 years since, enzymes and genes involved in the synthesis of hundreds of scent compounds from multiple plant species have been described. This review recapitulates this history and describes the major findings relating to the various aspects of floral scent biosynthesis and emission, including genes and enzymes and their evolution, storage and emission of scent volatiles, and the regulation of the biochemical processes.