Phenylpyruvate Contributes to the Synthesis of Fragrant Benzenoid-Phenylpropanoids in Petunia × hybrida Flowers

• Published in: Frontiers in plant science Vol. 8; p. 769
• Main Authors: Oliva, Moran, Bar, Einat, Ovadia, Rinat, Perl, Avichai, Galili, Gad, Lewinsohn, Efraim, Oren-Shamir, Michal
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 12.05.2017
• Subjects: benzenoid–phenylpropanoid; fragrant volatiles; PheA; phenylpyruvate; Plant Science; specialized metabolism; specialized metabolism; PheA; fragrant volatiles; benzenoid–phenylpropanoid; phenylpyruvate
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2017.00769

Phenylalanine (Phe) is a precursor for a large group of plant specialized metabolites, including the fragrant volatile benzenoid-phenylpropanoids (BPs). In plants, the main pathway leading to production of Phe is arogenate, while the pathway phenylpyruvate (PPY) is considered merely an alternative route. Unlike plants, in most microorganisms the only pathway leading to the synthesis of Phe is PPY. Here we studied the effect of increased PPY production in petunia on the formation of BPs volatiles and other specialized metabolites originating from Phe both in flowers and leaves. Stimulation of the pathway PPY was achieved by transforming petunia with , a gene encoding a bacterial feedback insensitive bi-functional chorismate mutase/prephenate dehydratase enzyme. overexpression caused dramatic increase in the levels of flower BP volatiles such as phenylacetaldehyde, benzaldehyde, benzyl acetate, vanillin, and eugenol. All three BP pathways characterized in petunia flowers were stimulated in flowers. In contrast, overexpression had only a minor effect on the levels of amino acids and non-volatile metabolites both in the leaves and flowers. The one exception is a dramatic increase in the level of rosmarinate, a conjugate between Phe-derived caffeate and Tyr-derived 3,4-dihydroxyphenylacetate, in PheA leaves. petunia flowers may serve as an excellent system for revealing the role of PPY in the production of BPs, including possible routes directly converting PPY to the fragrant volatiles. This study emphasizes the potential of the PPY route in achieving fragrance enhancement in flowering plants.