Nordström, Anders
(2004).
Cytokinins in Arabidopsis, tools, pathways and interaction with auxin.
Diss. (sammanfattning/summary)
Umeå :
Sveriges lantbruksuniv.,
Acta Universitatis Agriculturae Sueciae. Silvestria, 1401-6230
; 317
ISBN 91-576-6701-2
[Doctoral thesis]
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Abstract
Cytokinins are plant hormones, and their relative abundance in proportion to auxin determines whether shoots or roots are formed in callus tissue. The cytokinin to auxin ratio is also believed to regulate apical dominance in plants. The suggested biosynthetic route for cytokinin involves formation of the nucleotide iPMP as the first metabolite synthesized, which is then subsequently hydroxylated to form the nucleotide ZMP. In the work underlying this thesis the potential role of an iPMP-independent biosynthetic route, with direct formation of the nucleotide ZMP was explored. Using an inducible IPT line of Arabidopsis, and in vivo deuterium labelling coupled to analysis with LC-MS/MS, we concluded that ZMP could indeed be formed independently of iPMP. In a similar experiment with wild type Arabidopsis, ZMP was also formed independently of iPMP. Furthermore, the two plant hormones cytokinin and auxin have been shown to regulate each other’s metabolism. In experiments using the IAA analogue NAA, a very rapid decrease in the biosynthesis and pool size of cytokinins was observed. The effect of NAA was mediated through the iPMP-independent pathway. A negative effect of cytokinin on auxin biosynthesis and pool size was also detected. This regulation was found to be slower, and probably related to alterations in development. Arabidopsis and tobacco leaves and roots were separately incubated in media containing 2H2O. Cytokinin biosynthesis capacity was detected in all tissues, and small leaves seemed to possess the highest de novo biosynthesis capability. An Arabidopsis mutant defective in production of the ADK enzyme responsible for conversion of adenosine to adenosine 5´monophosphate and the corresponding cytokinins was found to contain elevated levels of cytokinins, while its IAA levels were lower than in wild type. The increased cytokinin content was due to increased cytokinin biosynthesis. Finally, a LC-MS/MS method capable of quantifying central cytokinin metabolites in sample sizes <50mg FW including bases, ribosides and intact nucleotides at a rate of 70 samples/day was developed.
Authors/Creators: | Nordström, Anders | ||||
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Title: | Cytokinins in Arabidopsis, tools, pathways and interaction with auxin | ||||
Series Name/Journal: | Acta Universitatis Agriculturae Sueciae. Silvestria | ||||
Year of publishing : | August 2004 | ||||
Number: | 317 | ||||
Number of Pages: | 53 | ||||
Papers/manuscripts: |
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Place of Publication: | Umeå | ||||
ISBN for printed version: | 91-576-6701-2 | ||||
ISSN: | 1401-6230 | ||||
Language: | English | ||||
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: | Not in use, please see Agris categories | ||||
Agrovoc terms: | cytokinins, auxins, biosynthesis, arabidopsis thaliana, chromatography, developemental stages | ||||
Keywords: | cytokinin, auxin, analysis, biosynthesis, Arabidopsis thaliana, liquid chromatography, ESI, MS/MS, interaction, development, plant hormones, derivatization | ||||
URN:NBN: | urn:nbn:se:slu:epsilon-293 | ||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-293 | ||||
ID Code: | 601 | ||||
Department: | (S) > Dept. of Forest Genetics and Plant Physiology | ||||
Deposited By: | Anders Nordström | ||||
Deposited On: | 18 Aug 2004 00:00 | ||||
Metadata Last Modified: | 02 Dec 2014 10:05 |
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