Molecular Control of Floral Fragrance

Abstract

Flowers of many plants attract pollinators by producing and emitting volatile compounds. The scent emitted by such flowers is typically a complex mixture of low-molecular-mass compounds (100–200 Da) which gives the flower its unique, characteristic fragrance. The chemical composition of flower fragrances varies widely among species in terms of the number, identity, and relative amounts of constituent volatile compounds (Knudsen and Tollsten, 1993; Knudsen et al.,1993). Such species-specific floral odors can enhance pollinator specificity, which in turn can reduce the chance of pollen loss and inappropriate interspecific pollination. Moreover, closely related plant species that rely on different types of insects for pollination produce different odors, reflecting the olfactory sensitivities or preferences of the pollinators (Henderson, 1986; Raguso and Pichersky, 1995). Characteristic floral odors are correlated with the type of pollinators. Species pollinated by bees and flies have sweet scents, whereas those pollinated by beetles have strong musty, spicy, or fruity odors (Dobson, 1994).