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Metabolism and homeostasis of indole-3-acetic acid in Arabidopsis thaliana

Kowalczyk, Mariusz (2002). Metabolism and homeostasis of indole-3-acetic acid in Arabidopsis thaliana. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae. Silvestria, 1401-6230 ; 256
ISBN 91-576-6340-8
[Doctoral thesis]

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The endogenous concentration of a primary auxin, indole-3-acetic acid (IAA) is regulated by a number of biochemical processes, including transport, biosynthesis, catabolism and conjugation. The studies on which this thesis is based focused on an instrumental approach for investigating pathways of IAA metabolism and for examining the IAA biochemistry in various Arabidopsis thaliana mutants. We have identified the major low molecular weight IAA at different concentrations. The endogenous presence of these metabolites was subsequently confirmed and their internal concentrations were measured using highly sensitive liquid chromatography-mass spectrometry (LC-MS) techniques. The results showed that non-decarboxylative oxidation of IAA is a key catabolic pathway in A. thaliana. The levels of selected ester and amide conjugates were very low, indicating either a rapid turnover or a low metabolite flux through the main conjugation pathways. Although the biosynthetic details of IAA amide conjugates remain unknown, an enzyme involved in ester conjugate biosynthesis was cloned and characterised at the biochemical level. The developed methods were subsequently used to analyse two mutants with suspected defects in auxin homeostasis, bus and sur2. In both cases we demonstrated that although IAA metabolism was profoundly altered, the cause of these alterations was not related to the hormone´s conjugation or catabolism. Instead, these mutations distorted the secondary metabolism of specific amino acids (methionine and tryptophan, respectively), which indirectly affected IAA biosynthesis. We also developed analytical tools to investigate proteins involved in IAA metabolism. In conjunction with standard protein analysis techniques, these methods can be used to identify enzymatic activities involved in IAA biosynthesis pathways, either dependent or independent of tryptophan. In relation to this, a second LC-MS technique for the in vivo determination of IAA precursors is also presented.

Authors/Creators:Kowalczyk, Mariusz
Title:Metabolism and homeostasis of indole-3-acetic acid in Arabidopsis thaliana
Series Name/Journal:Acta Universitatis Agriculturae Sueciae. Silvestria
Year of publishing :April 2002
Number of Pages:59
ALLI. Östin, A., Kowalczyk, M., Bhalerao, R. P. and Sandberg, G. (1998). Metabolism of indole-3-acetic acid in Arabidopsis. Plant Physiology, 118, 285-296. II. Barlier, I.*, Kowalczyk, M.*, Marchant, A.*, Ljung, K., Bhalerao, R., Bennett, M., Sandberg, G. and Bellini, C. (2000). The SUR2 gene of Arabidopsis thaliana encodes the cytochrome P450 CYP83B1, a modulator of auxin homeostasis. Proceedings of the National Academy of Sciences of the United States of America, 97, 14819-14824. III. Reintanz, B., Lehnen, M., Reichelt, M., Gershenzon, J., Kowalczyk, M., Sandberg G., Godde, M., Uhl, R. and palme, K. (2001). bus, a bushy Arabidopsis CYP79F1 knockout mutant with abolished synthesis of short-chain aliphatic glucosinolates. Plant Cell, 13, 351-367. IV. Jackson, R. G., Lim, E. K., Li, Y., Kowalczyk, M., Sandberg, G., Hoggett, J., Ashford, D. A. and Bowles, D. J. (2001). Identification and biochemical characterization of an Arabidopsis indole-3 acetic acid glucosyltransferase. Journal of Biological Chemistry, 276, 4350-4356. V. Dolušić, E., Kowalczyk, M., Magnus, V., Sandberg, G. and Normanly, J. (2001). Biotinylated indoles as probes for indole-binding proteins. Bioconjugate Chemistry, 12, 152-162. VI. Kowalczyk, M. and Sandberg, G. 2001. Quantitative analysis of indole-3-acetic acid metabolites in Arabidopsis. Plant Physiology, 127, 1845-1853. * To be considered joint first authors
Place of Publication:Umeå
ISBN for printed version:91-576-6340-8
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F60 Plant physiology and biochemistry
F Plant production > F61 Plant physiology - Nutrition
Subjects:Not in use, please see Agris categories
Agrovoc terms:arabidopsis thaliana, iaa, catabolism, homeostasis, biosynthesis, chromatography, mass spectrometry
Keywords:auxin, conjugation, catabolism, biosynthesis, liquid chromatography, mass spectrometry, multiple reaction monitoring
Permanent URL:
ID Code:215
Department:(S) > Dept. of Forest Genetics and Plant Physiology
Deposited By: Staff Epsilon
Deposited On:03 Apr 2003 00:00
Metadata Last Modified:02 Dec 2014 10:02

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