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Distribution and regulation of auxin in Arabidopsis root cells

Petersson, Sara (2011). Distribution and regulation of auxin in Arabidopsis root cells. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2011:59
ISBN 978-91-576-7603-0
[Doctoral thesis]

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The plant hormone auxin (IAA) coordinates many of the important processes in plant development. For example, IAA is critical for normal embryogenesis, root development, cell elongation, and the tropic responses such as gravitropism and phototropism. IAA gradients are established and maintained in many tissues and it is
thought that these gradients act as developmental cues, determining the fate of cells and tissues.

Descriptions of auxin distribution patterns with cellular resolution have previously been based solely on visual characterisation of auxin responsive reporter constructs. Measurements of the hormone gradient itself have been made in cambial sections of hybrid aspen and Pine, although even in this study, the measurements were not truly at cellular resolution.

In this thesis, I describe the measurement of IAA levels in the Arabidopsis root with cellular resolution. By combining the use of Arabidopsis lines expressing cellspecific GFP, Fluorescent Activated Flow Cytometry, and high-resolution mass spectrometry, I have provided the first analytical evidence for the presence of an IAA gradient in the Arabidopsis root apex. The work has enabled the development
of an auxin distribution map for the root with cellular resolution.

The IAA content of cells is actively regulated in order to maintain the IAA gradient. This regulation has been shown to be achieved through a combination of active transport and de novo biosynthesis. It has been proposed that IAA catabolism and conjugation also contribute to the regulation of hormone levels.

In this thesis, I present data supporting the hypothesis that catabolism, by converting IAA into its major inactive catabolite oxIAA, contributes to the regulation of the levels of free IAA. I also present data showing a role for the plant hormone cytokinin in the dynamic regulation of IAA biosynthesis in response to changing developmental and environmental conditions.

Authors/Creators:Petersson, Sara
Title:Distribution and regulation of auxin in Arabidopsis root cells
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :20 May 2011
Number of Pages:82
IPetersson, S.V., Johansson, A.I., Kowalzcyk, M., Makoveychuk, A., Wang, J.Y., Moritz, T., Grebe, M., Benfey, P.N., Sandberg, G. and Ljung, K. (2009): An Auxin Gradient and Maximum in the Arabidopsis Root Apex Shown by High Resolution Cell Specific Analysis of IAA Distribution and Synthesis. Plant Cell 21(6), 1659-1668.
IIPetersson, S.V., Henyková, E., Simon, S., Greenham, K., Novák, O.,Kowalzcyk, M., Estelle, M., Zazímalová, E., Sandberg, G. and Ljung, K.(2011): IAA catabolism - an important regulator of auxin homeostasis in Arabidopsis. (Manuscript).
IIIJones, B.*, Gunnerås, S.A.*, Petersson, S.V.*, Tarakowski, P., Graham, N., May, S., Dolezal, K., Sandberg, G. and Ljung, K. (2010): Cytokinin Regulation of Auxin Synthesis in Arabidopsis Involves a Homeostatic Feedback Loop Regulated via Auxin and Cytokinin Signal Transduction. Plant Cell 22(9), 2956-2969.
Place of Publication:Umeå
Publisher:Institutionen för skoglig genetik och växtfysiologi, Sveriges lantbruksuniversitet
ISBN for printed version:978-91-576-7603-0
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F60 Plant physiology and biochemistry
F Plant production > F62 Plant physiology - Growth and development
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Analytical Chemistry
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Biochemistry and Molecular Biology
Agrovoc terms:auxins, arabidopsis thaliana, roots, mass spectrometry, catabolism, cytokinins
Keywords:Auxin, Arabidopsis thalinana, root, GFP, Fluorescent Activated Cell Sorting, IAA, oxIAA, catabolism, cytokinin
Permanent URL:
ID Code:8192
Department:(S) > Dept. of Forest Genetics and Plant Physiology
Deposited By: Ph.D Sara Petersson
Deposited On:21 Jun 2011 06:17
Metadata Last Modified:02 Dec 2014 10:46

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