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Schnitzler, J.-P. ; Madlung, J. ; Rose, A. ; Seitz, H.-U.

Biosynthesis of p-hydroxybenzoic Acid in Elicitor-treated Carrot Cell Cultures.

Planta 188, 594-600 (1992)
Open Access Green as soon as Postprint is submitted to ZB.
Carrot (Daucus carota L.) cells respond to treatment with fungal elicitors by synthesizing wall-bound p-hydroxybenzoic acid (p-HBA). The biosynthetic pathway to p-HBA is still hypothetical. Tracer experiments with L-phenylalanine indicate the involvement of the general phenylpropanoid pathway. 3,4 (Methylenedioxy)-cinnamic acid, an inhibitor of hydrocycinnamate: CoA ligase, inhibits the accumulation of anthocyanins in carrot, while it does not interfere with p-HBA synthesis. Thus p-HBA biosynthesis does not appear to involve CoA thioesters. In the present report the sequence of enzymic reactions leading to p-HBA was investigated in vitro using protein preparations from cells treated with a fungal elicitor from Pythium aphanidermatum (Edson) Fitzp. The side-chain degradation from p-coumaric acid to p-HBA is not analogous to the beta-oxidation of fatty acids and involves p-hydroxybenzaldehyde as an intermediate. The final step from p-hydroxybenzaldehyde to p-HBA is catalyzed by an NAD-dependent p-hydroxybenzaldehyde dehydrogenase (EC 1.2.1.-). This reaction was characterized with regard to cofactor requirements, pH and temperature optima. The in-vitro formation of p-HBA from p-coumaric acid and the activity of the hydroxybenzaldehyde dehydrogenase are moderately elicitor-induced but to a much lesser extent than phenylalanine ammonia-lyase, which is the starting enzyme of the general phenylpropanoid pathway.
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Publication type Article: Journal article
Document type Scientific Article
ISSN (print) / ISBN 0032-0935
e-ISSN 1432-2048
Journal Planta
Quellenangaben Volume: 188, Issue: 4, Pages: 594-600 Article Number: , Supplement: ,
Publisher Springer
Reviewing status Peer reviewed
Institute(s) Institute of Biochemical Plant Pathology (BIOP)