Mass-spectrometric quantitation of cytokinins in tobacco crown-gall tumours induced by mutated octopine Ti plasmids of Agrobacterium tumefaciens |
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Authors: | Brian A. McGaw Roger Horgan Jim K. Heald George J. Wullems Rob A. Schilperoort |
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Affiliation: | (1) The Rowett Research Institute, Greenburn Road, Bucksburn, AB2 9SB Aberdeen, UK;(2) Department of Botany and Microbiology, University College of Wales, SY23 3DA Aberystwyth, Dyfed, UK;(3) Department of Experimental Botany, Research Group in Molecular Plant Physiology, Botanical Laboratory, University of Nijmegen, Toernooiveld, NL-6525 ED Nijmegen, The Netherlands;(4) Department of Plant Molecular Biology, State University of Leiden, Wassenaarseweg 64, NL-2333 AL Leiden, The Netherlands |
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Abstract: | The levels of the major cytokinins, zeatin, zeatin riboside, zeatin riboside-5 -monophosphate and zeatin-7-glucoside were measured in tobacco (Nicotiana tabacum L.) crown-gall tissues carrying insertion and deletion mutations in the T-DNA. Measurements were made by combined gas chromatography-mass spectrometry using selected ion monitoring with 15N- and 2H-labelled internal standards. The results demonstrate that, relative to wild-type tumour tissue, cytokinin levels are considerably elevated in tissues lacking functional T-DNA auxin-biosynthetic genes. From a detailed analysis of the major cytokinin metabolites it is concluded that a reduction in the extent of cytokinin degradation via N6-side-chain cleavage is an important factor leading to increased cytokinin levels in these tissues.Abbreviations IAA indole-3-acetic acid - SIM selected ion monitoring - Z zeatin - [7G]Z zeatin-7-glucoside - [9R]Z zeatin-9-riboside - [9R-5 P]Z zeatin riboside-5 -monophosphate |
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Keywords: | Agrobacterium Auxin in tumors Cytokinin (in tumors, turnover, oxidase) Mutant (T-DNA) Nicotiana (crown gall) T-DNA mutants |
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