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The role of actin cytoskeleton in the targeting of auxin carriers to the plasma membrane.
Kebrlová, Štěpánka ; Petrášek, Jan (advisor) ; Pernisová, Markéta (referee)
Auxin plays an important morphogenic role in plant development, mainly through its effect on gene expression, but also through a number of faster processes that are directly dependent on its concentration. Therefore, in many plant tissues, directional auxin transport using specific transporters in the plasma membrane, is important for the coordination of morphogenic stimuli. The amount of auxin carriers in the plasma membrane directly affects the resulting auxin concentration inside the cell. Although the localization of auxin transporters and their abundance in the plasma membrane could be determined primarily by the actin cytoskeleton and its involvement in vesicle transport processes, this relationship is currently still unclear. Therefore, in this study, we were interested in how the localization and function of auxin transporters is affected when the function of the actin cytoskeleton is affected in a given cell type. To this end, the localization of the auxin transporters PIN3, PIN4, PIN7, and AUX1 was studied in epidermal cells of cotyledons in young seedlings of Arabidopsis thaliana whose morphogenesis was affected by mutations in subunits of the actin nucleation complex ARP2/3. Crosses of mutants in the ARP2/3 complex subunits with marker lines carrying fluorescently labeled auxin carriers...
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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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The role of cytoskeleton in auxin transport
Kebrlová, Štěpánka ; Petrášek, Jan (advisor) ; Mašková, Petra (referee)
Auxins are a class of plant hormones (phytohormones) with their most frequently endogenously occurring representative indol-3-acetic acid (IAA). Because of their influence on division and elongation of cells, auxins play an important role in many developmental and physiological processes such as embryo development, vascular tissue patterning and tropisms. These effects are often mediated by polar auxin transport, which results in a wide variety of auxin concentrations in cells and entire tissues. Transport of auxin from cell to cell is partly mediated by diffusion, the prevalence of auxin transport is however mediated by auxin carriers located on plasma membrane (PM). Among such carriers belong AUX1/LAX (AUXIN RESISTANT 1/LIKE AUX1) transporter family, which helps with auxin influx and families of PIN-FORMED (PIN) and ABCB/PGP (ATP-binding cassette subfamily B/P-glycoprotein) transporters, which take part in auxin efflux. These proteins are in various degrees dependent on a system of membrane vesicles, trafficking along actin cytoskeleton, which ensures among others cycling of these vesicles among PM and endosomal cell space. Regulation of auxin transport is possible on multiple levels including influencing of gene expression for carrier proteins and regulation of their localization, activity and...
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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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Auxin Transport in Arabidopsis thaliana: From the whole plant to suspension cultured cells
Seifertová, Daniela ; Zažímalová, Eva (advisor) ; Opatrný, Zdeněk (referee) ; Hejátko, Jan (referee)
in English Plants with their sessile life-style are exposed to many stimuli from environment. They have developed mechanisms how to coordinate their growth and development, which allows them to survive sometimes in very difficult conditions. Plant hormones are one of the most important regulators of this signal transduction. Auxins, as the oldest known group of plant hormones, play important role in many physiological processes in plants. To allow perceiving the information in every single cell, auxin molecule is transported by cell-to-cell manner. Auxin molecules enter the cell by passive diffusion or by active uptake by auxin influx carriers. To reach the next cell, they are transported actively out of the cell by auxin efflux carriers. Athough active auxin transport has been studied for almost four decades, past two decades contributed to the identification and characterization of particular auxin carriers remarkably. This thesis contributes to the knowledge on the auxin efflux and influx carriers and their involvement in the processes occurring from a single cell level to the level of a whole plant. Firstly, it brings detailed description of auxin transport characteristics in Arabidopsis thaliana cell suspension cells (Ath cells). Secondly, it shows that the overproduction of PIN1 auxin efflux...
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