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Discovery of General Controů Nondereprssible 5 protein interactors using proximity labeling
Potapenkova, Uliana
Usually, proteins don’t act as isolated species, but they perform their function in complexes with other proteins. Identification of protein-protein interactions (PPIs) brings insights into regulation of plant developmental processes and their response to the environmental conditions. In recent years, several methods to study PPIs were developed, since they represent the key objectives of plant system biology research. This thesis is focused on the Proximity Labeling (PL) assay in order to study GCN5 protein interactors. GCN5 is a histone acetyltransferase that plays a crucial role in plants’ defense responses to various abiotic stresses. Studies of its interactors provide valuable information on the histone acetylation mechanisms and the way plants cope with adverse conditions. Here, the advantages and disadvantages of PL assay are summarized and compared with other methods of PPIs studies. In the experimental part of this work, GCN5 was cloned and plasmid for further biotin-based proximity labeling was prepared.
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Tolerance Pavlownia tomentosa in vitro k suchu a osmotické zátěži
Zapalač, Radek
This diploma thesis deals with the influence of abiotic stressors on plant growth and their acclimation responses. An in vitro culture experiment was conducted with Paulownia tomentosa plants for 35 days, in which growth parameters (reduction of leaf turgescence, leaf damage, plant height, number of nodes per stem, number of leaves and number of roots) and plant survival, under the treatment of three different osmotics at different concentrations in the medium (20 g/l sucrose – control, 80 g/l sucrose, 50 mM NaCl, 100 mM NaCl, 1.5 % PEG6000, 3 % PEG6000). On days 10 and 30 of the experiment, plant samples were collected for determination of ABA and proline content in leaves. The radioimmunoassay method was used to determine ABA content, while proline content was determined by spectrophotometric measurement. During the first ten days of cultivation, gas samples were also taken from the culture vessels to determine ethylene production, which was subsequently carried out by gas chromatography. The results obtained were statistically and graphically processed and supplemented by photodocumentation.
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Vliv nízké teploty na propustnost buněčných membrán a přežití rostlin
Kubovčíková, Anna
Plants are naturally exposed to low temperatures in nature. During the winter, the temperatures are the lowest and in certain places they even reach very low values. Jasmonic acid plays an important role in the plant's resistance to low temperatures. In the thesis, we have focused on the effect of the PLIP genes that produce precursors of jasmonic acid. The role of the genes in cold resistance in Arabidopsis thaliana was studied after acclimation in different light conditions. The observed parameters in plants acclimated to low temperatures were the parameters of photosynthesis, intactness of cell membranes and survival after exposure to freezing. The results of the experiments proved that the mutation of the PLIP genes cause a decrease in the integrity of the cell membranes when exposed to freezing, and conversely, the ectopically increased expression of the PLIP3 gene results in an increase in plant resistance. Based on ion leakage, we determined LT50 values for each variant, and it was shown that the difference between the most resistant transgenic line plip3 ox and the mutant line in all three PLIP genes is more than 4 °C. Subsequently, a plant survival test after freezing was performed, where it was demonstrated that the LT50 value correlated with plant survival. Chlorophyll fluorescence analysis showed that after acclimation to low temperature, there are no large differences in photosynthetic parameters between individual genotypes with modified PLIP level. The light that was applicated during acclimation had a more pronounced effect on the plants. Plants acclimated at low intensity showed higher values of non-photochemical quenching as well as greater maximum quantum yield of photosystem II. The results prove that the PLIP genes are significantly involved in the resistance of plants to low temperatures.
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Study of the autophagosome biogenesis in Arabidopsis
Ničová, Veronika
The process of autophagy is a cellular mechanism that allows cells to dispose of both damaged and unwanted components. These components are covered by a double membrane, from which an autophagosome arises. Afterwards, the content is transported to the vacuole, where it is degraded or recycled. Due to the immobility of plants, they have evolved a number of mechanisms for defending themselves from adverse conditions. It is well known that autophagy occurs throughout the life of a plant, but it can be intensified if needed, for example in the event of a stressful condition. In view of the fact that autophagy is a relatively complex regulated mechanism, there is an ongoing effort to conduct research on this topic. Therefore, autophagy is important in stress condition responses, whether they are caused by biotic or abiotic factors. There are various types of stress that can influence autophagy in different ways, including poorly packaged proteins or the availability of nutrients. Additionally, autophagy is not only essential for the tolerance to certain applied stresses, but it is also essential for the regulation of stress memory. Functional characterization of phosphatidylinositol-3-phosphates role in autophagy and phagophore biogenesis is also very important. As part of this thesis, the mtv11 mutant plant was monitored. The mutant plants carry a mutation in the MTV11 gene that encodes an important subunit of the phosphoinositide 3-kinase complex. Plants were monitored under abiotic stress conditions to study their effects on autophagosome formation. A study of this mutant plant might be contributing to the accurate understanding of the autophagosome biogenesis.
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Funkční profilování komponentů komplexu transkripčních koaktivátorů SAGA v Arabidopsis
Sokolov, Rodion
Regulation of gene expression can be carried out by various mechanisms, one of them is enzyme-mediated modification of histones. Such enzymes often form large multi-subunit complexes to facilitate their enzymatic activity and substrate specificity. The Spt-Ada-Gcn5 acetyltransferase (SAGA) complex is a complex of transcriptional coactivators highly conserved between plants and yeast. In plants, SAGA can regulate gene expression through histone acetylation and deubiquitination. PHYTOCHROME-DEPENDENT LATE-FLOWERING (PHL)/SPT20 is a subunit of the structural module SAGA, that interacts with phytochrome B and thus regulates flowering, but at the same time its expression affects plant response to drought and nitrogen deficiency. In the experimental part of this work, the effect of PHL on resistance to other abiotic stresses, such as oxidative and osmotic stress was investigated. The response of plants defective in the gene encoding PHL to the given stresses was shown to be dependent on the photoperiod, whereby the impact of oxidative stress was more pronounced when grown under long-day conditions. On the contrary, plants were more sensitive to osmotic stress under short-day conditions. In this study, the metabolites present in the phl mutant line at a different concentration than in the standard plants were identified and may thus be responsible for the different response of this line to stress.
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Response to abiotic stress in plants growing in green façades of temperate urban environment
Hrochová, Růžena ; Lhotáková, Zuzana (advisor) ; Havelková, Lenka (referee)
With increasing urbanization the temperature of cities is increasing and an effect of urban heat island arises. Vegetation, particularly vertical greenery systems: facades and walls, is mitigating urban heat island and reducing temperature. The aim of this work was to define these systems, their effects on the urban microclimate, to create an overview of the most used plants for greenery systems and to summarize their reactions to abiotic stresses of cities in a temperate region. Mediterranean studies were used in this work due to the scarcity of temperate climate research, which results could become valuable with climate change. Selecting proper vegetation can be done using habitat template, plants that are acclimated or adapted to the urban environment. Plants affect the urban microclimate through shading and transpirational cooling, which ideally contribute to reducing the heat island effect with optimal irrigation. Stressors followed in this work were drought, high temperature and irradiance, air pollution and salinity. To all these stressors plants reacted with limiting physiological functions and reducing growth. The common reaction was a decrease photosynthesis rate and chlorophyll content. Ractions of plants of vertical greenery systems to different stressors and their combinations are...
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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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The importance of root exudates for crop cultivation under climate change
Schnürer, Oliver ; Albrechtová, Jana (advisor) ; Tylová, Edita (referee)
Root exudates are compounds secreted by plant roots that can help plants, for example, to obtain nutrients from the soil or to increase their resistance to biotic stress. Root exudates can thus hide a great potential that can be used in agriculture. As human population grows, there is increasing pressure on agriculture, which must provide enough food to feed the global population, thus ensuring food security. Until now, agricultural activity has tried to satisfy this demand by intensification of agriculture, mainly by breeding highly productive crops when using intensive fertilizing, but the theoretical possible benefits of root exudates in breeding remained overlooked. Intensive farming practices can further exacerbate the impacts of ongoing climate change, for example by increasing soil carbon mineralization or reducing biodiversity. By using root exudates in the production of crops, it will be possible to achieve a higher nutrient content in soil, as well as a higher resistance of crops to pests, without the aforementioned negative impacts of intensive agriculture. In this work, I tried to describe the main functions of root exudates, their reaction to increased CO2 concentration in the atmosphere, their stress response caused by stressors of climate change and their theoretical use in...
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Physiological basis of the tradeoff between growth and defense against abiotic stress: the role of carbon balance
Doložílek, Jakub ; Konrádová, Hana (advisor) ; Petrášek, Jan (referee)
Similarly to other organisms, plants must coordinate growth and development with their energetic status. Besides that, considering their sessile way of life, they need to adapt very precisely to the environmental conditions of their habitats. However, from the point of view of invested resources, the defence mechanisms may be very expensive, and so, their activation is usually accompanied by a restriction of growth. Hence, establishing functional dynamic balance between investment to growth and defensive reactions ("G-D tradeoff") is essential for the plants fitness, competitiveness and reproduction success. The thesis examines the mechanisms that are fundamentally contributing to this balancing. In this work, evolutionarily conserved axis coordinating growth and development with energetic status consisting of TOR kinase, positive growth regulator during favourable conditions, and her antagonist, the SnRK kinase, inducer of resources mobilization in purpose of realizing defensive measures securing energetic homeostasis, is discussed. Further, this thesis focuses on plant-specific pathway which links the TOR-SnRK1 axis with perception of environmental conditions. The main components of this pathway are the SnRK2 kinases, coordinators of specific defensive reactions, PP2C phosphatases and...
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Chromatin remodeling during temperature sensing in plants
Šlesingerová, Terezie
The evolutionary conserved transcriptional co-activator Spt–Ada–Gcn5 Acetyltransferase (SAGA) complex in Arabidopsis thaliana is tightly involved in numerous cellular processes by histone posttranslational modifications. The GENERAL CONTROL NON-REPRESSED PROTEIN 5 (GCN5), a SAGA subunit, is a histone acetyltransferase that impacts chromatin remodeling. Arabidopsis mutants lacking GCN5 are sensitive to heat stress, but the molecular mechanisms implicating GCN5 in heat stress are currently unknown. To get an insight into the molecular pathways underlying the heat sensitivity of gcn5, we assessed global proteome changes triggered by heat stress in the gcn5 background. Even though most of the identified proteins responded similarly both in gcn5 and wild type plants, some of them like CONSTITUTIVE PHOTOMORPHOGENIC 11 (COP11) were unaffected by heat in the gcn5 mutant background but decreased drastically in the wild type. We further screened mutants affected in putative GCN5 interactors under heat stress and identified that lack of SAGA COMPLEX SUBUNIT 2A (SCS2A) and INHIBITOR OF GROWTH 1 (ING1) results in heat sensitivity. Taken together, our results pave the way for a more detailed understanding of the role of GCN5 in stress responses.
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