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.
Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA.
Jennifer
J
Boatright
Florence
F
Negre
Xinlu
X
Chen
Christine M
CM
Kish
Barbara
B
Wood
Greg
G
Peel
Irina
I
Orlova
David
D
Gang
David
D
Rhodes
Natalia
N
Dudareva
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