Biosynthesis of floral scent 2-phenylethanol in rose flowers

Plants emit chemically diverse volatile compounds for attracting pollinators or putting up a chemical defense against herbivores. 2-Phenylethanol (2PE) is one of the abundantly emitted scent compounds in rose flowers. Feeding experiments with l-[(2)H8]phenylalanine into rose flowers and subsequent analysis using gas chromatography-mass spectrometry analysis revealed the hypothetical biosynthetic intermediates to [(2)H8]-2PE, and the biochemical and genetic analyses elucidated the principal pathway to [(2)H8]-2PE. We recently found season-specific 2PE pathway producing [(2)H7]-2PE from l-[(2)H8]phenylalanine. This is a unique example where the dominant pathway to a specific compound changes with the seasons. This review focuses on the biosynthesis of floral volatiles and their regulation to adapt to the changes in the environment.