Document Detail

Accumulation of p-hydroxybenzoic acid in hairy roots of Daucus carota 2: confirming biosynthetic steps through feeding of inhibitors and precursors.
MedLine Citation:
PMID:  19342120     Owner:  NLM     Status:  MEDLINE    
Biosynthesis of hydroxybenzoates even at enzymatic level is poorly understood. In this report, effect of feeding of putative biosynthetic precursors and pathway-specific enzyme inhibitors of early phenylpropanoid pathway on p-hydroxybenzoic acid accumulation in chitosan-elicited hairy roots of Daucus carota was studied. Three selective metabolic inhibitors of plant phenylpropanoid pathway, namely, aminooxyacetic acid (AOAA), piperonylic acid (PIP) and 3,4-methylenedioxycinnamic acid (MDCA), which are known to inhibit phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL) respectively, the three early enzymes of phenylpropanoid metabolism, were chosen with the anticipation that selective inhibition of these enzymes in vivo may provide information on the metabolic route to p-hydroxybenzoic acid formation. Supplementation of AOAA (0.2-1.0 mM) and PIP (0.2-1.0 mM) resulted in the reduced accumulation of p-hydroxybenzoic acid in the wall-bound fraction. However, addition of MDCA (0.2-1.25 mM), did not suppress p-hydroxybenzoic acid accumulation but suppressed lignin and total flavonoid accumulation, suggesting that 4CL enzyme activity is not required for p-hydroxybenzoic acid formation. Feeding of elicited hairy roots with phenylalanine, coumaric acid and p-hydroxybenzaldehyde had a stimulatory effect on p-hydroxybenzoic acid accumulation; however, maximum stimulatory effect was shown by p-hydroxybenzaldehyde. This suggests that p-hydroxybenzaldehyde might be the immediate precursor in p-hydroxybenzoic acid biosynthesis. Finally, in vitro conversion of p-coumaric acid to p-hydroxybenzoic acid with p-hydroxybenzaldehyde as intermediate using cell-free extract provided an unequivocal support for CoA-independent and non-beta-oxidative route of p-hydroxybenzoic acid biosynthesis in Daucus carota.
Debabrata Sircar; Adinpunya Mitra
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-04-01
Journal Detail:
Title:  Journal of plant physiology     Volume:  166     ISSN:  1618-1328     ISO Abbreviation:  J. Plant Physiol.     Publication Date:  2009 Sep 
Date Detail:
Created Date:  2009-08-03     Completed Date:  2009-12-07     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882059     Medline TA:  J Plant Physiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  1370-80     Citation Subset:  IM    
Natural Product Biotechnology Group, Agricultural & Food Engineering Department, Indian Institute of Technology Kharagpur, Kharagpur 721 302, India.
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MeSH Terms
Aminooxyacetic Acid / pharmacology
Benzoates / pharmacology
Biosynthetic Pathways* / drug effects
Cell-Free System / drug effects
Cells, Cultured
Chitosan / pharmacology
Cinnamates / pharmacology
Coenzyme A Ligases / antagonists & inhibitors
Coenzymes / pharmacology
Daucus carota / cytology,  drug effects*,  enzymology,  metabolism*
Enzyme Inhibitors / pharmacology*
Lignin / metabolism
Parabens / chemistry,  metabolism*
Phenylalanine Ammonia-Lyase / metabolism
Plant Roots / cytology,  drug effects*,  enzymology,  metabolism*
Time Factors
Reg. No./Substance:
0/Benzoates; 0/Cinnamates; 0/Coenzymes; 0/Enzyme Inhibitors; 0/Parabens; 621-82-9/cinnamic acid; 645-88-5/Aminooxyacetic Acid; 9005-53-2/Lignin; 9012-76-4/Chitosan; 94-53-1/piperonylic acid; 99-96-7/4-hydroxybenzoic acid; EC Ammonia-Lyase; EC 6.2.1.-/Coenzyme A Ligases; EC ligase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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