A peroxisomally localized acyl-activating enzyme is required for volatile benzenoid formation in aPetunia×hybridacv. ‘Mitchell Diploid’ flower

• Published in: Journal of experimental botany Vol. 63; no. 13; pp. 4821 - 4833
• Main Authors: Colquhoun, Thomas A., Marciniak, Danielle M., Wedde, Ashlyn E., Kim, Joo Young, Schwieterman, Michael L., Levin, Laura A., Van Moerkercke, Alex, Schuurink, Robert C., Clark, David G.
• Format: Journal Article
• Language: English
• Published: OXFORD UNIVERSITY PRESS 01-01-2012
• Subjects: Amino acids; Biochemistry; Biosynthesis; Enzymes; Flowers; Genes; Peroxisomes; Petals; Plants; RESEARCH PAPER; RNA
• ISSN: 0022-0957; 1460-2431

Floral volatile benzenoid/phenylpropanoid (FVBP) biosynthesis is a complex and coordinate cellular process executed by petal limb cells of aPetunia×hybridacv. ‘Mitchell Diploid’ (MD) plant. In MD flowers, the majority of benzenoid volatile compounds are derived from a core phenylpropanoid pathway intermediate by a coenzyme A (CoA) dependent, β-oxidative scheme. Metabolic flux analysis, reverse genetics, and biochemical characterizations of key enzymes in this pathway have supported this putative concept. However, the theoretical first enzymatic reaction, which leads to the production of cinnamoyl-CoA, has only been physically demonstrated in a select number of bacteria likeStreptomyces maritimusthrough mutagenesis and recombinant protein production. A transcript has been cloned and characterized from MD flowers that shares high homology with anArabidopsis thalianatranscriptACYL-ACTIVATING ENZYME11(AtAAE11) and theS. maritimus ACYL-COA:LIGASE(SmEncH). In MD, thePhAAEtranscript accumulates in a very similar manner as bona fide FVBP network genes, i.e. high levels in an open flower petal and ethylene regulated.In planta, PhAAE is localized to the peroxisome. Upon reduction ofPhAAEtranscript through a stable RNAi approach, transgenic flowers emitted a reduced level of all benzenoid volatile compounds. Together, the data suggest that PhAAE may be responsible for the activation oft-cinnamic acid, which would be required for floral volatile benzenoid production in MD.