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KT/HAK/KUP High-affinity Transporters in Plants
Šustr, Marek ; Tylová, Edita (advisor) ; Vaňková, Radomíra (referee) ; Gloser, Vít (referee)
Due to its essential role in plant metabolism and often low availability in the soil, sufficient potassium uptake and management are among the challenges plants face to survive in different environments. Since all potassium functions are related to the transport of the monovalent cation K+ , research focuses on the transporters responsible for K+ uptake and allocation. In addition to playing an essential role in potassium nutrition, K+ transporters also mediate the uptake of pollutants such as Cs. Radioisotopes 134 Cs and 137 Cs released from nuclear bomb tests and nuclear power plant accidents remain in the environment and their accumulation in plants is being studied to reveal the risks of crop production in contaminated soils as well as the possibility of remediating contaminated soil through plants. Ion transport also seems to be a major driver of plant adaptation to unfavourable environments. Several ion transporters appear to be involved in the adaptation of Arabidopsis arenosa populations to serpentine soils, including the potassium transporter AaKUP9. This thesis summarises my effort to characterise two transporters from KT/HAK/KUP family, AtKUP7 and AtKUP9, in Arabidopsis thaliana, and related projects. For AtKUP9, I have significantly expanded the knowledge of its involvement in...
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Mechanisms and regulation of callose deposition to the cell wall of Arabidopsis thaliana
Modráčková, Jana ; Kulich, Ivan (advisor) ; Šustr, Marek (referee)
Callose (β-1,3-glucan) is a significant plant cell wall polysaccharide, which participates in many developmental and stress responses. Despite the importance of this polymer, the knowledge on the causes of callose synthesis, its regulation and the meaning of callose deposition are still limited. The family of callose synthases was revealed thanks to molecular and genetic methods. They are responsible for callose deposition in diferent reactions and the diferent spaces of the plant body. This thesis summarizes the knowleadge about the processes, in which callose is involved, and it presents an overview of the individual proteins from callose synthase family including their phylogenetic analysis and the comparison with the cellulose synthase focusing on the model plant Arabidopsis thaliana. Key words: Arabidopsis thaliana, β-1,3-glucan, callose, callose synthase, plant cell wall polymer
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Mechanisms and regulation of callose deposition to the cell wall of Arabidopsis thaliana
Modráčková, Jana ; Kulich, Ivan (advisor) ; Šustr, Marek (referee)
Callose (β-1,3-glucan) is a significant plant cell wall polysaccharide, which participates in many developmental and stress responses. Despite the importance of this polymer, the knowledge on the causes of callose synthesis, its regulation and the meaning of callose deposition are still limited. The family of callose synthases was revealed thanks to molecular and genetic methods. They are responsible for callose deposition in diferent reactions and the diferent spaces of the plant body. This thesis summarizes the knowleadge about the processes, in which callose is involved, and it presents an overview of the individual proteins from callose synthase family including their phylogenetic analysis and the comparison with the cellulose synthase focusing on the model plant Arabidopsis thaliana. Key words: Arabidopsis thaliana, β-1,3-glucan, callose, callose synthase, plant cell wall polymer
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Involvement of AtKT/HAK/KUP high-affinity transporters in plant K+ and Cs+ uptake
Šustr, Marek ; Tylová, Edita (advisor) ; Maršík, Petr (referee)
Potassium is essential macroelement and large amount of potassium is taken up by plants, because it's the major osmotic of plant cell. Due to various potassium availability in different kinds of soil, plants have evolved transport system that can maintain sufficient K+ uptake between several orders of magnitude of potassium concentration. In Arabidopsis thaliana mechanism of K+ acquisition is well understood and it's known that AtHAK5 is mainly involved in K+ uptake in its very low concentrations. AtHAK5 belongs to KT/HAK/KUP family that consist 13 members in A. thaliana. There's known function for some members for example in auxin transport in root tip (TRH1) or in K+ efflux in stomatal closure (KUP6). In this thesis possible involvement of yet unstudied transporters KUP5, KUP7, KUP9 and KUP10 in K+ acquisition and homeostasis in A. thaliana was investigated. In vitro cultivation showed that kup9 mutant has very short lateral roots in K+ deficiency. On the other hand kup5 mutant showed significantly higher dry weight in K+ deficiency than Col-0. Kup9 phenotype was successfully replicated in subsequent cultivations and anatomy of lateral root apical meristems was investigated. Root tips of kup9 were differently organized in K+ deficiency and they showed signs of early termination of meristems. To...
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Uptake and metabolism of 137Cs in plants
Šustr, Marek ; Tylová, Edita (advisor) ; Maršík, Petr (referee)
Plants are able to uptake radiocesium from soil, which is the potential route to enter the food chain. Cesium mobility in soil is determined by clay particles. Cesium can be reversibly ad- sorbed on their surface or can be fixed between layers. Mineral illit has the highest selectivity for cesium due to its frayed edges. Organic matter determines cesium mobility only in soil with organic matter content above 90 %. Cesium is more available for plants in this soil. Cesium uptake varies among species. Many plant species accumulating big amounts of cesium belong to family Chenopodiaceae. Cesium uptake is affected by other cations in soil solution. Potassium is the most effective one. Increasing of external potassium concentration from 50 μM to 250 μM decreased cesium uptake thirty-fold. Potassium affects cesium mobili- ty in soil and plant uptake. Due to chemical similarities of cesium and potassium some potassium transporters efficiently transport both cations. Potassium transporters are therefore considered the main entrance site in plant roots. Great contribution to cesium uptake is dedi- cated to high-affinity potassium transporter HAK5. Another great part of cesium uptake is mediated by non-selective cation channels. Plants can uptake up to 80 % of cesium applied on shoot surface. Cesium is highly...
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