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Structural modification of the root cortex in response to environmental conditions
Lehmannová, Justýna ; Tylová, Edita (advisor) ; Albrechtová, Jana (referee)
Plants encounter many adverse factors in their environment to which they must adapt in order to make effective use of their environment despite stresses such as water shortage, nutrient deficiency, soil salinization, soil compaction or flooding. This work focuses on the internal structure of the root and its changes in response to environmental stress conditions. Specifically, it focuses on structural modifications of the middle part of the root cortex, which play an important role in optimizing root system functions under stress conditions. It summarizes knowledge on the structure, mode of formation and regulatory mechanisms of aerenchyma formation, which is of great importance for plant survival under hypoxic conditions. These are encountered by many plants in flooded areas, including important agricultural crops such as rice and maize. This paper also analyses the role of aerenchyma in response to other stress factors such as nutrient deficiency, water deficit or substrate compaction. In addition, this work focuses on lesser-known structural modifications of the middle part of the cortex, whose function has not yet been fully understood, but which represent potentially important characteristics of the root system that could be the focus of future breeding of resistant crop cultivars. These...
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Root - shoot junction (collet) development
Hermann, Jiří ; Žárský, Viktor (advisor) ; Tylová, Edita (referee)
Although the root-shoot junction (collet) of adult plants is a well-identifiable part of the plant body, its development has, surprisingly till now, escaped serious research attention. The junction is a key region in the life of plants, as it connects two contrasting plant life environments and involves important changes in developmental programs - underground vs aboveground. The junction in angiosperms is first established during the embryogenesis phase of development in the form of the broad embryonic root- hypocotyl transition region, and it continues to develop further after seed germination during the individual's growth. The most important organ in this process is the hypocotyl, which exhibits considerable developmental plasticity, allowing extraordinary elongation in etiolated dark growth but also initiating formation of adventitious roots upon the deetiolation. During each stage of the junction's development, auxin signalling and polar auxin transport play a crucial role. Most of the research focuses on the development of the junction in the model organism Arabidopsis thaliana. The significance of the phylogenetic origin of the junction is also discussed from the perspective of the evolutionary origin of roots vs shoots and embryos evolution. This work aims to provide an overview of the...
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The role of plant root exudates for soil carbon sequestration
Bourdais, Lukáš ; Albrechtová, Jana (advisor) ; Tylová, Edita (referee)
Global climate change is a process that affects us all today and will continue to affect us with increasing intensity in the future. An important way to reduce the concentration of CO2 in the atmosphere is the sequestration of carbon in pools other than the atmosphere, primarily in the soil pool. One way to achieve this is by increasing the carbon sequestration into the soil biomass using root exudates. Root exudates are released by plant roots into the soil to be beneficial to the plant and are also a good source of carbon for the rhizosphere (the soil in the immediate vicinity of the root system affected by its exudates). The rhizosphere is thus a suitable environment for microorganisms that play a major role in the soil carbon sequestration. In this thesis, I describe the composition and the role of root exudates for the plant, the importance of root border cells and border-like cells, the importance of exuded carbon coumpounds for microorganisms in the soil and their importance for carbon sequestration and CO2 mineralization in the soil. The role of root exudates and microorganisms in the soil carbon cycle is discussed with an emphasis on mineral-associated soil organic carbon and soil aggregates. This thesis also discusses the role of exudates for the rhizosphere priming effect and its...
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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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Variability in the response of exodermis to nutrient deficiencies in the environment
Klvaňová, Renáta ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
v angličtině Plant growth and development is largely dependent on the soil environment which is a source of minerals and water needed for plants to survive. However, the availability of these resources in the soil is very heterogenous and important elements can be leached into the lower parts of the soil or bound to soil particles. Plants have therefore developed a number of adaptations during evolution to increase the efficiency of the root system. One of these aspects are the apoplastic barriers (endodermis and exodermis). Both of these layers affect the transport of substances to and from the root, thereby limiting unregulated apoplastic transport through modifications of the cell walls where the polymers that limit the transport of substances are deposited. These are Casparian bands and suberin lamellae. They often differentiate more rapidly when plants are faced with a stress factor such as drought, salinity or toxicity. However, nutrient deficiencies (e.g. N, P, K and Fe) also affect the rate of differentation. Deficiencies can result in both acceleration and deceleration of differentation, which seems to help optimize root transport properties according to the current conditions. However, this reaction has been less studied so far. This work therefore focuses on the analysis of the response...
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Mechanisms of transmembrane auxin transport in a broader evolutionary context.
Rubešová, Magdaléna ; Petrášek, Jan (advisor) ; Tylová, Edita (referee)
Auxin, represented by the molecule indole-3-acetic acid (IAA), is one of the main phytohormones involved in the regulation of plant development. Its intercellular transport establishes concentration gradients in individual cells that control gene expression and a number of downstream processes. In plants, a complex mechanism for efficient IAA transport has evolved, involving both long-distance transport and intercellular transport within individual tissues. Because our understanding of the auxin transport mechanisms is still incomplete, this thesis attempts to summarize the literature data on all modes of auxin transport across cell membranes that have been recognized to date and places them in a broader evolutionary context. The presence of IAA in many prokaryotic and eukaryotic organisms, together with the similarly wide occurrence of carriers from "auxin efflux carrier" transporter family, evolutionarily related PIN-FORMED-like carriers, points to the possibility that IAA transport may also be evolutionarily very ancient and may functionally derive from more general mechanisms of ions or amino acids.
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Plant growth on saline soils - interaction of sodium and potassium in plant metabolism
Peřinová, Anna ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Soil salinity represents a significant stress factor that negatively affects plant growth and is also a current problem in modern agriculture. This bachelor's thesis focuses on the mechanisms associated with this stress, with a main emphasis on the effects of excess sodium cations in the soil, their accumulation in plants, the mechanism of their negative impact, and defense strategies. It addresses the importance of potassium and sodium in plant nutrition and metabolism, as the interference of Na+ with the essential functions of K+ is an important aspect of the stress caused by salt excess in the environment. The thesis analyzes the most important transporters and channels that ensure the uptake and transport of K+ and Na+ in plants. Emphasis is placed mainly on the transport of sodium and the mechanisms that enable plants to adapt to saline environments and tolerate higher concentrations of salts in the soil, particularly the SOS defense system against Na+ accumulation in the cytoplasm and unique structures that allow salt secretion in halophytic plants. Attention is also directed to the difference between glycophytic and halophytic plants.
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Mineral nutrient transporters and root system efficiency
Schmidová, Dominika ; Tylová, Edita (advisor) ; Kobercová, Eliška (referee)
Plants are sessile organisms whose survival depends largely on the ability to ensure sufficient water and mineral nutrient uptake by the root system. To this end, plants have evolved specialised transport systems that ensure selective uptake of essential elements and also allow plants to adapt to varying soil nutrient concentrations. In terms of transport kinetics, mineral nutrient transporters are of two types - high-affinity and low-affinity. Depending on the nutrient concentration in the soil, plants can engage each type to maximise nutrient uptake. In addition to the efficient setup of transport processes at the membranes, there are other mechanisms in the plant to maximize the uptake of soil resources. These are mainly changes in the architecture of the root system. In addition to the systemic growth response, plants regulate root growth at the local level in response to uneven nutrient distribution in the soil. This response is limited to a specific part of the root system, which adapts to use that area as efficiently as possible. In addition to their transport function, mineral nutrient transporters also play a sensory role in the regulation of localised root growth. The aim of this bachelor thesis is to describe the uptake mechanism of the important essential macronutrients, nitrogen,...
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Hormonal responses to cold stress
Šturma, Vít ; Vaňková, Radomíra (advisor) ; Tylová, Edita (referee)
Low temperatures are an increasingly common stress factor for plants. Sudden and intense temperature fluctuations are thus a serious cause for lower crop yields. For this reason, it is important to understand what mechanisms are used by plants to defend themselves against damage caused by cold and freezing. An important component of this defence is represented by plant hormones, phytohormones, which create a complex network of signalling pathways. Phytohormones then control via their signalling pathways plant responses to cold stress. A few phytohormones affect the plant ability to cope with the cold stress, and the interactions among all these phytohormones are important for an efficient response to cold and freezing. Recently, research has revealed that the complex signalling network has a greater impact than previously thought. The phytohormone research in relation to cold stress responses is attracting more and more attention. The main aim of this thesis is to summarize the current knowledge on the role of phytohormones in the responses to cold stress. The thesis describes the signalling pathways of individual phytohormones and clarifies how the components of these pathways are involved in the response to cold stress. Also, the dynamics of phytohormone levels and signalling components in...
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Specifics of plant mineral nutrition on serpentine soils
Škopová, Lucie ; Tylová, Edita (advisor) ; Lhotáková, Zuzana (referee)
Serpentine is a metamorphosed ultramafic rock on which a substrate with specific combinations of properties responsible for creating the typical inhospitable conditions for plant life is formed. The characteristic chemical composition of serpentine soils consists of a low ratio of Ca:Mg ions, low content of biogenic elements (P, K, N) and a high concentration of heavy metals (Co, Cr, Ni). Abiotic factors such as rocky surface, shallow soil and lack of water also hinder the life of local plant. The aim of this bachelor thesis was to summarize the complex of characteristic serpentine phenomenon that in many ways create stress conditions for plants growth. Thanks to this specificity, the serpentine areas are characterised by a specific flora and vegetation with a number of endemics. This work focuses on the specific mineral nutrition of plants and summarizes the knowledge on the mechanisms of adaptation of plants growing on serpentine substrates. I focused mainly on the typical low Ca:Mg ion ratio in serpentine soil and described the functions of these elements in plants and the stress effect of excess Mg. Throughout this work, I also address the mechanisms of uptake and transport of serpentine-relevant nutrients in the plants identified so far. In conclusion, I discuss ability of plants to survive in...
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