Regulators of floral fragrance production and their target genes in petunia are not exclusively active in the epidermal cells of petals

• Published in: Journal of experimental botany 2012-05, Vol.63 (8), p.3157-3171
• Main Authors: Van Moerkercke, Alex, Galván-Ampudia, Carlos S., Verdonk, Julian C., Haring, Michel A., Schuurink, Robert C.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; ATP binding cassette transporters; ATP-Binding Cassette Transporters - chemistry; ATP-Binding Cassette Transporters - genetics; ATP-Binding Cassette Transporters - metabolism; Biological and medical sciences; Biosynthesis; Cell Membrane - metabolism; Cell membranes; Epidermal cells; Flowers; Flowers - cytology; Flowers - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Genes; Genes, Plant - genetics; Intracellular Space - metabolism; Mesophyll cells; Molecular Sequence Data; Molecular Weight; Odorants; Organ Specificity - genetics; Petals; Petunia - cytology; Petunia - genetics; Plant Epidermis - cytology; Plant Epidermis - genetics; Plant physiology and development; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Promoter Regions, Genetic - genetics; Protein Transport; Protoplasts; Protoplasts - metabolism; RESEARCH PAPER; Research Papers; RNA, Messenger - genetics; RNA, Messenger - metabolism; Subcellular Fractions - metabolism
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/ers034

In which cells of the flower volatile biosynthesis takes place is unclear. In rose and snapdragon, some enzymes of the volatile phenylpropanoid/benzenoid pathway have been shown to be present in the epidermal cells of petals. It is therefore generally believed that the production of these compounds occurs in these cells. However, whether the entire pathway is active in these cells and whether it is exclusively active in these cells remains to be proven. Cell-specific transcription factors activating these genes will determine in which cells they are expressed. In petunia, the transcription factor EMISSION OF BENZENOIDS II (EOBII) activates theODORANT1(ODO1) promoter and the promoter of the biosynthetic geneisoeugenol synthase(IGS). The regulator ODO1 in turn activates the promoter of the shikimate gene5-enolpyruvylshikimate-3-phosphate synthase(EPSPS). Here the identification of a new target gene ofODO1, encoding an ABC transporter localized on the plasma membrane,PhABCG1, which is co-expressed withODO1, is described.PhABCG1expression is up-regulated in petals overexpressingODO1through activation of thePhABCG1promoter. Interestingly, theODO1, PhABCG1, andIGSpromoters were active in petunia protoplasts originating from both epidermal and mesophyll cell layers of the petal, suggesting that the volatile phenylpropanoid/benzenoid pathway in petunia is active in these different cell types. Since volatile release occurs from epidermal cells, trafficking of (volatile) compounds between cell layers must be involved, but the exact function of PhABCG1 remains to be resolved.