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Transport and Metabolism of Radio-Labelled Cytokinins in Plant Cells and Tissues
Nedvěd, Daniel ; Ryšlavá, Helena (advisor) ; Vaňková, Radomíra (referee)
Cytokinins are a large group of phytohormones. Since their discovery in the 1950s, they have shown to play a pivotal role in plant physiology. Most studies so far focused on cytokinin action mechanisms and their metabolic regulation. Identification of AtABCG14 and AtPUP14 as cytokinin-specific membrane carriers brought researchers' attention to cytokinin membrane transport, too. In this thesis, we performed experiments with radio-labelled cytokinin tracers. We show that trans-zeatin and isopentenyladenine, two major biologically active cytokinins, are readily transported across the plasma membrane in tobacco BY-2 cell suspension. Making use of mathematical modelling, we show that BY-2 cells possess a membrane transport system with an affinity toward cytokinins. Next, we show that atabcg14 and atpup14 mutations affect cytokinin metabolism in Arabidopsis thaliana plants. Keywords: cytokinin, Arabidopsis thaliana, tobacco BY-2 cell lines, membrane transport, purine permease, ATP-binding cassette, radio-labelling
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Transport and Metabolism of Radio-Labelled Cytokinins in Plant Cells and Tissues
Nedvěd, Daniel ; Ryšlavá, Helena (advisor) ; Vaňková, Radomíra (referee)
Cytokinins are a large group of phytohormones. Since their discovery in the 1950s, they have shown to play a pivotal role in plant physiology. Most studies so far focused on cytokinin action mechanisms and their metabolic regulation. Identification of AtABCG14 and AtPUP14 as cytokinin-specific membrane carriers brought researchers' attention to cytokinin membrane transport, too. In this thesis, we performed experiments with radio-labelled cytokinin tracers. We show that trans-zeatin and isopentenyladenine, two major biologically active cytokinins, are readily transported across the plasma membrane in tobacco BY-2 cell suspension. Making use of mathematical modelling, we show that BY-2 cells possess a membrane transport system with an affinity toward cytokinins. Next, we show that atabcg14 and atpup14 mutations affect cytokinin metabolism in Arabidopsis thaliana plants. Keywords: cytokinin, Arabidopsis thaliana, tobacco BY-2 cell lines, membrane transport, purine permease, ATP-binding cassette, radio-labelling
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Mechanism of cytokinin transport across plasma membrane
Nedvěd, Daniel ; Ryšlavá, Helena (advisor) ; Dračínská, Helena (referee)
Cytokinins are one of major groups of phytohormones, signaling molecules participating on the crucial physiological processes of plants. Regulation of their function is mostly associated with metabolic changes, recent identification of membrane proteins AtABCG14 and AtPUP14 as selective cytokinin transporters has brought up the possibility of the regulation of cytokinin signalization via polar membrane transport, though. Using the accumulation of radioactively labeled cytokinins in transgenic BY-2 cell culture, we studied the kinetics of cytokinin transport via AtABCG14 and AtPUP14 transporters at cellular level and possible changes of cytokinin metabolism linked to elevated expression of these transporters. Elevated expression of AtPUP14 transporter led to elevated accumulation of labeled cytokinins in form of both ribosides and free bases, while it had no effect on metabolism of labeled cytokinins. Elevated expression of AtABCG14 had no effect on accumulation of labeled cytokinins in BY-2 cells. (In Czech) 1
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