Minisymposium 5: Secondary Metabolism

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Abs # M0504: Understanding benzenoid metabolism in petunia flowers

Presenter:	Dudareva, Natalia       Contact Presenter
Authors	Schnepp, Jennifer  (A)   Orlova, Irina  (A)   Marshall-Colon, Amy  (A)   Varbanova, Marina  (B)   Fridman, Eyal  (B)   Rhodes, David  (A)   Pichersky, Eran  (B)   Dudareva, Natalia  (A)
Affiliations:	(A): Purdue University, West Lafayette (B): University of Michigan, Ann Arbor

The biosynthesis of benzenoid compounds requires the shortening of the carbon skeleton side chain by a C₂ unit, which can potentially occur via either the CoA-dependent - β-oxidative pathway, CoA-independent - non-β-oxidative pathway, or a combination of both. In vivo stable isotope labeling in combination with computer-assisted metabolic flux analysis of the benzenoid network in petunia flowers revealed that both the CoA-dependent - β-oxidative and CoA-independent - non-β-oxidative pathways contribute to the formation of benzenoid compounds. According to the model, the flux through the CoA-independent - non-β-oxidative pathway with benzaldehyde as a key intermediate was estimated to be about two times higher than the flux through the CoA-dependent - β-oxidative pathway. In addition, the modeling showed that benzylbenzoate is also an intermediate between L-Phe and benzoic acid. Silencing of BPBT, the enzyme that uses benzoyl-CoA and benzylalcohol (or phenylethanol) to make benzylbenzoate (or phenylethylbenzoate), eliminated benzylbenzoate and phenylethylbenzoate formation and led to a significant expansion of the emission of benzylalcohol, phenylethanol, benzylaldehyde, and phenylacetaldehyde, as well as benzylacetate and phenylethylacetate. A reduced level of benzoic acid in flowers of transgenic plants confirmed that benzylbenzoate is one of the intermediates in benzoic acid biosynthesis from phenylalanine.