ODORANT1 Regulates Fragrance Biosynthesis in Petunia Flowers

• Published in: The Plant cell 2005-05, Vol.17 (5), p.1612-1624
• Main Authors: Julian C. Verdonk, Haring, Michel A., van Tunen, Arjen J., Schuurink, Robert C.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Benzene Derivatives - metabolism; Biosynthesis; Circadian Rhythm - physiology; Developmental stages; Down-Regulation - physiology; Emissions; Flowers; Flowers - metabolism; Gels; Gene expression regulation; Gene Expression Regulation, Plant - physiology; Genes; Molecular Sequence Data; Petals; Petunia - metabolism; Phylogeny; Pigmentation; Plant cells; Plant Proteins - genetics; Plant Proteins - isolation & purification; Plant Proteins - metabolism; Plant reproduction; Plants; Pollen - physiology; Pollinators; Repressor Proteins - genetics; Reproduction - physiology; RNA; Sequence Homology, Nucleic Acid; Shikimate pathway; Shikimic Acid - metabolism; Signal Transduction - physiology; Silencer Elements, Transcriptional - physiology
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.104.028837

Floral scent is important to plant reproduction because it attracts pollinators to the sexual organs. Therefore, volatile emission is usually tuned to the foraging activity of the pollinators. In Petunia hybrida, volatile benzenoids determine the floral aroma. Although the pathways for benzenoid biosynthesis have been characterized, the enzymes involved are less well understood. How production and emission are regulated is unknown. By targeted transcriptome analyses, we identified ODORANT1 (ODO1), a member of the R2R3-type MYB family, as a candidate for the regulation of volatile benzenoids in Petunia hybrida cv W115 (Mitchell) flowers. These flowers are only fragrant in the evening and at night. Transcript levels of ODO1 increased before the onset of volatile emission and decreased when volatile emission declined. Downregulation of ODO1 in transgenic P. hybrida Mitchell plants strongly reduced volatile benzenoid levels through decreased synthesis of precursors from the shikimate pathway. The transcript levels of several genes in this pathway were reduced by suppression of ODO1 expression. Moreover, ODO1 could activate the promoter of the 5-enol-pyruvylshikimate-3-phosphate synthase gene. Flower pigmentation, which is furnished from the same shikimate precursors, was not influenced because color and scent biosynthesis occur at different developmental stages. Our studies identify ODO1 as a key regulator of floral scent biosynthesis.