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Plant hormones homeostasis: auxin and cytokinin crosstalk
Doležálková, Lucie ; Zažímalová, Eva (advisor) ; Dračínská, Helena (referee)
5 AbstractAbstractAbstractAbstract It has been since 19th century when the phytohormones and their crosstalk became one of the central themes in plant biology. Due to advances in molecular biology there is number of metabolic pathways linked to certain groups of plant hormones revealed by now, nevertheless much remains to be determined about their cooperation. The aim of this thesis is to evaluate the effect of exogenous cytokinin application on oat leaf segments (Avena sativa) - both specifically towards other phytohormones levels and generally in physiological context (in relation to their senescence). Our results confirmed increased auxin levels due to exogenous application of selected cytokinins and identified biological activity of trans-zeatin-9-glucoside (previously considered as irreversibly deactivated cytokinin type substance) in respective plant model. (In Czech) Key words: phytohormones, auxin, cytokinin, Avena sativa, senescence assay
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Mechanizmus transportu cytokininů přes buněčnou membránu a jejich metabolizmus v buňkách tabákové suspenzní kultury BY-2
Klíma, Petr ; Zažímalová, Eva (advisor) ; Galuszka, Petr (referee) ; Procházka, Stanislav (referee)
MECHANISM OF CYTOKININ TRANSPORT ACROSS PLASMA MEMBRANE AND THEIR METABOLISM IN TOBACCO BY-2 CULTURED CELLS Mgr. Petr Klíma / Abstract of Ph.D. Thesis / Prague 2011 Cytokinins (CKs) are plant hormones that play a major role in a number of developmental processes in plants. Those include promotion of cell division, active growth and differentiation, and maintenance of sink-source relationships, as well as control of environmental stress responses. Native CKs are low-molecular derivatives of adenine which seem to act either as paracrine or as long-distance signals. Due to their numerous physiological effects, plants have to precisely control the occurrence of bioactive CK molecules on the levels of the whole plant, its organs, tissues as well as single cells. To achieve this, a concerted action of metabolism and transport processes is required. Studies of the kinetics of CK translocation across plasma membrane in BY-2 suspension-grown tobacco cells suggested the existence of energy-dependent, partially selective transport routes for CK bases and CK ribosides. HPLC analysis of the metabolites of accumulated CKs pointed at their fast degradation or metabolic conversion into physiologically inactive forms. The prevalent ways of inactivation were the degradation to adenine and phosphorylation or phosphoribosyl...
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Mechanismy regulace aktivity vynašečů auxinu
Křeček, Pavel ; Zažímalová, Eva (advisor) ; Novotná, Zuzana (referee) ; Reinöhl, Vilém (referee)
The morphology of plant body is shaped by genetically coded developmental programme together with environmental factors. The influence of environmental factors on the morphology is much more important in plants that in other multicellular organisms. The developmental programme provides a general scheme that is modified by environmental signals. Phytohormone auxin is a regulator of plant morphogenesis and its distribution in the plant body is an important mechanism controling the growth and development of plants and coordinating the developmental programme with environmentally-induced changes. This thesis investigates factors important for transport of auxin from cells, second part is dedicated to bioinformatic analysis of the transporters from the PIN protein family. For investigation of signals involved in regulation of activity of auxin efflux transporters I have selected (based on published information) physiological signals influencing auxin transport. These signals were changed by treatment with chemicals and resulting changes in auxin transport were measured (on the cellular level) with the intention to discover signals that can rapidly (within minutes) change the activity of auxin efflux transporters. The signals, which satisfy these requirements were subjected to further investigation. He detailed...
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Rodina auxinových přenašečů PIN: funkční a evoluční pohled
Skůpa, Petr ; Zažímalová, Eva (advisor) ; Hejátko, Jan (referee) ; Opatrný, Zdeněk (referee)
Growth and development of plant body is dependent on correct and effective integration of information about current deployment of its body parts, as well as on perception and transduction of inputs from environment. Multiple developmental processes within plant body are determined by specific and tightly controlled distribution of molecule with unique signaling mission within plant development - auxin. Spatial distribution of auxin is co-determined by plethora of tightly controlled processes, and the polar auxin transport plays unique role among them. PIN proteins are the plant-specific family of secondary transporters driving movement of auxin across membranes. With their frequent asymmetrical localization within cells, specific expression patterns in developing tissues and their reactiveness to external cues they secure unique, dynamic and asymmetric distribution of auxin within the plant body. This dissertation thesis is focused on characterization of the role different PIN proteins play in determining cellular auxin homeostasis and consequent formation of auxin gradients. Controlled overexpression of PIN proteins in tobacco cells showed, that PIN4 and to some extent also PIN6, function as the direct auxin efflux carriers. In the cellular auxin transport they play the role analogous to other...
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Význam rostlinných proteinů z podrodiny ABCB pro transport auxinu
Kubeš, Martin ; Zažímalová, Eva (advisor) ; Hejátko, Jan (referee) ; Reinöhl, Vilém (referee)
Polar auxin transport provides essential directional and positional information for many developmental processes in plants. At the cellular level, it is realized by both passive diffusion and the active transport through the membrane proteins - AUX1/LAXes, PINs and ABCBs. The aim of this thesis was to characterize the role of ABCB1, ABCB4 and ABCB19 proteins in polar auxin transport using transformed tobacco BY-2 cell lines. It was shown that the plasma membrane (PM) localization of the ABCB1, 4 and 19 is not polar. The ABCB4 was also more stable on PM after the treatment with auxin influx inhibitors; making use of ABCB4-cell line helped to uncover new characteristics of markers of endocytosis - the FM- dyes. The induction of ABCB19 has led to a decrease in 3 H-NAA accumulation with characteristic auxin starvation phenotype, similar to PIN7 overexpressing cell line, that could be rescued in case of PIN7 cell line by application of the auxin efflux inhibitor NPA; however, the accumulation of auxin in ABCB19-overexpressing cell line was less sensitive to NPA and the rescue of the auxin starvation phenotype was ineffective. Importantly, unique property of the ABCB4 was demonstrated: It displayed dual, auxin-concentration-dependent auxin transport activity in Arabidopsis roots, tobacco BY-2 and yeast cells. The...
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Analyzing the complexity of auxin-related processes and their regulation
Simon, Sibu ; Zažímalová, Eva (advisor) ; Stiborová, Marie (referee) ; Pavlíček, Jiří (referee)
Phytohormone auxin plays an important role in various aspects of plant growth and development. The necessary concentration maxima at the region of its action are achieved by auxin metabolism, passive diffusion of auxin molecules across plasma membrane and by the carrier-mediated auxin transport, as well as by modulation of these processes. In our study we used a group of compounds structurally related to major endogenous auxin indole-3-acetic acid, as well as synthetic auxins 2,4-dichlorophenoxy acetic acid (2,4- D) and naphthalene-1-acetic acid (NAA). We aimed to characterize the auxin specificity of developmentally important processes such as carrier-mediated auxin transport, and 'genomic' (transcriptional) and 'non-genomic' (transcriptional) auxin signaling. In addition to the characterization of these compounds we also hoped to get an insight into the complex regulatory mechanism of auxin-related processes and to possibly find a particular compound with distinct behavior towards particular processes. By making use of such compounds and other molecular tools we aimed to analyze the mechanism of 'non-genomic' auxin signaling, to understand the mode of action of FM (Fei Mao) styryl dyes on the dynamics of membrane- localized auxin transporters, and to study the involvement of other phytohormones...
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Molecular mechanism of transport of plant hormone auxin into cells
Laňková, Martina ; Zažímalová, Eva (advisor) ; Stiborová, Marie (referee) ; Opatrný, Zdeněk (referee)
The non-uniform distribution of the plant growth regulator (phytohormone) auxin is known to mediate many fundamental processes in plant development. Auxin is transported through the plant body either via vascular pathways or from cell to cell by specialized polar auxin transport machinery. This machinery consists of a balanced system of passive diffusion combined with the activities of auxin influx and efflux carriers. This work is focused on the processes that are involved in the uptake of auxin into plant cells. On the basis of molecular-biological and biochemical characterization, the function as an auxin influx carrier was confirmed for PaLAX1 protein from wild cherry (Prunus avium). The sequences of isolated cDNA of the PaLAX1 gene and of its protein product are highly similar to both the cDNAs and the corresponding protein products of the AUX1/LAX-type genes, coding for putative auxin influx carriers in model plant A. thaliana. On the level of organs and single cells, we have shown that the overproduction of PaLAX1 in transgenic lines resulted in an increase of the content of native auxin indole-3-acetic acid as well as of the uptake of synthetic auxin, 2,4-dichlorophenoxyacetic acid. Further, the mechanism of action of putative auxin influx inhibitors 1-naphthoxyacetic acid (1-NOA),...
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The role of tubulin transport between the nucleus and the cytoplasm
Bokvaj, Pavel ; Schwarzerová, Kateřina (advisor) ; Zažímalová, Eva (referee)
Tubulin is the basic building block of microtubules which ensure intracellular transport, morphological changes, the connection of proteins of metabolic pathways, the segregation of chromosomes during mitosis and many other essential processes in plant cells. The localization of tubulin regarding nucleus is strictly controlled and during the interphase, tubulin is usually not present in the nucleus. As we previously showed, one of the exceptions of the presence of tubulin in the nucleus is the cold stress condition. Also, we discovered several plant-specific nuclear export sequences (NES) in tubulin molecules: one in α-tubulin and two in β-tubulin. In this work I found that double mutation of both functional β-tubulin NESes cause slight accumulation of the protein in the nuclei. However, the phenotype of the transgenic plants expressing β-tubulin with mutations is probably not affected by the presence of the mutated protein. The effect of the expression of the mutated β-tubulins was observed in Nicotiana tabacum BY-2 cells as well. The expression of β-tubulin carrying a single NES3 mutation or double mutation of both NESes bring changes of the division activity of the cells, while the NES2 mutation does not have any effect. Furthermore, it was discovered that the 0řC cold tr eatment does not cause...
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AUXIN BINDING PROTEIN 1 (ABP1) and its role in the auxin management in plant cells
Čovanová, Milada ; Zažímalová, Eva (advisor) ; Lüthen, Hartwig (referee) ; Reinöhl, Vilém (referee)
Conclusions The role of AUXIN BINDING PROTEIN 1 (ABP1) in the auxin management in plant cells was followed using simplified model material of suspension-cultured cells of tobacco BY-2 line. ABP1 is a putative auxin receptor considered to mediate fast non-genomic responses to auxin and it can be involved in every aspect of the regulation of auxin responses, metabolism and transport. There are four major conclusions that could be made based on the results presented in this thesis: 1) Auxin binding protein 1 mediates both cell division and expansion in tobacco BY-2 cells. In standard cultivation conditions or at lower concentrations of 2,4-D in culture medium, ABP1 overexpression had no detectable impact on cell division, cell elongation or cell growth.. 5- times increased 2,4-D concentration stimulated weakly cell elongation. . Antisense suppression of ABP1 expression resulted in disturbance in both cell expansion and cell division intensity, suggesting that ABP1 is essential for the control of balance between cell division and cell elongation during the growth cycle. ABP1 is localized in endoplasmic reticulum of cells cultivated in standard medium supplemented with 1 μM 2,4-D and it appeared also at the plasma membrane following the IAA application. 2) ABP1 mediates intercellular auxin transport. Cells...
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