Understanding in vivo benzenoid metabolism in petunia petal tissue.
In vivo stable isotope labeling and computer-assisted metabolic flux analysis were used to investigate the metabolic pathways in petunia (Petunia hybrida) cv Mitchell leading from Phe to benzenoid compounds, a process that requires the shortening of the side chain by a C(2) unit. Deuterium-labeled Phe ((2)H(5)-Phe) was supplied to excised petunia petals. The intracellular pools of benzenoid/phenylpropanoid-related compounds (intermediates and end products) as well as volatile end products within the floral bouquet were analyzed for pool sizes and labeling kinetics by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. Modeling of the benzenoid network revealed that both the CoA-dependent, beta-oxidative and CoA-independent, non-beta-oxidative pathways contribute to the formation of benzenoid compounds in petunia flowers. The flux through the CoA-independent, non-beta-oxidative pathway with benzaldehyde as a key intermediate was estimated to be about 2 times higher than the flux through the CoA-dependent, beta-oxidative pathway. Modeling of (2)H(5)-Phe labeling data predicted that in addition to benzaldehyde, benzylbenzoate is an intermediate between l-Phe and benzoic acid. Benzylbenzoate is the result of benzoylation of benzyl alcohol, for which activity was detected in petunia petals. A cDNA encoding a benzoyl-CoA:benzyl alcohol/phenylethanol benzoyltransferase was isolated from petunia cv Mitchell using a functional genomic approach. Biochemical characterization of a purified recombinant benzoyl-CoA:benzyl alcohol/phenylethanol benzoyltransferase protein showed that it can produce benzylbenzoate and phenylethyl benzoate, both present in petunia corollas, with similar catalytic efficiencies.
Boatright
Jennifer
J
Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA.
Negre
Florence
F
Chen
Xinlu
X
Kish
Christine M
CM
Wood
Barbara
B
Peel
Greg
G
Orlova
Irina
I
Gang
David
D
Rhodes
David
D
Dudareva
Natalia
N
D000217:Acyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001547:Benzaldehydes / Q000378:metabolism; D001555:Benzene Derivatives / Q000378:metabolism*; D001565:Benzoates / Q000378:metabolism; D017124:Conserved Sequence; D035264:Flowers / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D032306:Petunia / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D001547:Benzaldehydes; D001555:Benzene Derivatives; D001565:Benzoates; C044605:methyl benzoate; D000217:Acyltransferases; C032175:benzaldehyde