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Light and its effect on plant proteome
Luklová, Markéta
Light is one of the main environmental factors largely determining plant life. Light provides energy resources for photosynthesis and it is also the most important medium of perception as it represents the main source of information about plant surroundings. My diploma thesis entitled “Light and its effect on plant proteome” briefly summarizes present knowledge about the light perception in plants, its interpretation of light quality, quantity, and direction via photoreceptors. These components trigger a whole range of changes, both on molecular and developmental levels, but the complex molecular mechanisms regulating system of light signalling in plants are far from being resolved. Here, I followed effects of different light parameters on plant proteome, namely, diurnal variations, low- and high-light intensity, spectral composition, and a change in the light period duration. To study these effects two model organisms were selected (i) Arabidopsis thaliana as a representative plant model with the most annotated genome/proteome and (ii) Solanum lycopersicum as a representative plant model significant for agriculture and biotechnology. Proteome changes in response to different light factors were analyzed by LC-MS. In total, the analyses revealed over 100 and 300 light-responsive proteins in Arabidopsis and S. lycopersicum, respectively. Proteomics provided highly sensitive snapshots of protein abundance in response to light and selected experiments have been complemented with a GC-MS metabolite profiling, conductivity measurements, and fluorescence microscopy.
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Štúdium interakcie rastlinných hormónov cytokinínov a signálnej dráhy UV svetla
Kameniarová, Michaela
Photomorphogenesis is a developmental process in which plants change their growth and morphology in response to the light conditions. Besides the visible part of the light, photomorphogenic responses are also mediated by UV light. UV light responses include hypocotyl growth inhibition, cotyledon extension and biosynthesis of flavonoids. Another important factor in photomorphogenesis are the plant hormones cytokinins which affect many aspects of plant life. The aim of the bachelor thesis was description of interactions of cytokinins with the signalling pathway of UV light. Perception of UV light is mediated by photoreceptor UVR8. The effect of exogenous CK addition on the expression of selected CK and UVR8 regulated genes was monitored by RT-qPCR in 7 days-old Arabidopsis thaliana seedlings with mutation in UVR8, and the effect of CK on the growth of their roots and hypocotyls was monitored as well. Gene expression analysis showed that the mutation in UVR8 gene interfere with cytokinin signalling.
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Vliv specifické aplikace zvýšené teploty na vývoj a produkci modelové rostliny Solanum lycopersicum L. kultivar Micro-Tom
Bařinková, Magda
Temperature fluctuations are currently the most serious abiotic factors that negatively affect plant growth and development, as well as seed and fruit production. It is assumed that up to 70 % yield of crops is reduced due to suboptimal environmental conditions. Although these factors have a demonstrably negative effect on yields of crops, the question is whether they can be modified to positively stimulate plant growth and development. The bachelor thesis is focused on the influence of the changing temperature conditions on the growth and development of the model tomato plant (Solanum lycopersicum L.) cultivar Micro-Tom. Basic growth parameters such as size and plant generation time, size and shape of the fruit showed a positive impact of heated soil on tomato plants development. Last but not least, the targeted transcriptomic analysis revealed that plants growing in the heated soil contain an altered expression of genes related to signaling and metabolic pathways of cytokinin, abscisic acid, ethylene and gibberellins. This corresponds with the positive impact of heated soil on the fruit development and ripening.
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Význam cytokininů v indukci kvetení při různých teplotních podmínkách
Blechová, Veronika
Global climate change i sone of the most serious environmental problém and its negative socio-economic consequences represent serious threats for sustainable agriculture in many countries. Sudden increase in ambient temperature by a few °C over the plant optimal growth temperature, causes flower abortion or damage of the fruits, and thus reduce productivity and yield in agriculture. Cytokinins are important phytohormones which are involved in regu-lation of the growth and development but their role in the plant adaptation to increased ambient temperature is not well understood. The aim of this work was description of the role of cytoki-nins in the thermomorphogenesis and plants transition into generative phase under different temperature regimes in Arabidopsis thaliana. Experiments with transgenic plants with modu-lated cytokinin levels showed that decreased cytokinin levels has great impact on the plant growth and temperature could even potentiate this effect. Cytokinins were shown to induce flowering and this effect was independent of the ambient temperature. As next, it was found that higher ambient temperature has great impact on the seed production It was proven that cultivation plants at 29 °C cause pollen abortion independently of cytokinin levels.
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Vliv vybraných stanovištních faktorů na proteolytickou aktivitu lesních půd s důrazem na organické a anorganické látky
Holík, Ladislav
PhD thesis focuses on soil biochemistry, namely the effects of organic and inorganic substances on proteolytic ktivity in forest soils. The thesis is composed of several impacted journal articles and two manuscripts. Selected organic compounds feature L- and D-tartaric acid, phenolics, proteinogenic and non-proteinogenic amino acids, auxins and cytokinins, whilst inorganic substances are represented by salts. Furthermore, an article dealing with the effects of different forest management practises on soil enzymatic ktivity (including proteases) is adjoined. Its aim is to monitor the effect of forest regenerative elements (forest stand gaps) on enzymatic ktivity, whereas the intervention into forest ktivity changes the moisture and thermal conditions of the site. The results show that out of the organic substances tested L- and D-tartaric acid, proteinogenic and non-proteinogenic amino acids and auxins have a positive effect on the proteolytic ktivity. Conversely, phenols and cytokinins acted as inhibitors. Soil salinization also had a negative effect on proteolytic ktivity of forest soils. The Influence of forest management through forest regenerative elements on soil protease ktivity was not detected. Potential urease ktivity was the only enzyme that reacted to the change of climatic conditions of forest habitat; however, ktiv not a principal topic of this work.
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Narušení metabolismu proteinů a jeho efekt na růst rostlin
Luklová, Markéta
Recent years have shown that plant hormones operate through circuits in which targeted, conditional turnover of regulator proteins via proteasome are of critical importance. Thus, a disruption of the ubiquitin-proteasome system (UPS) would have a significant impact on plant growth and development. This thesis entitled Protein metabolism disruption and its effect on plant growth reviews the mechanisms of proteasome-mediated targeted degradation and analyzes its role in plant hormone cytokinin signaling. The experimental part is divided into two sections (i) growth response analyzes and (ii) an LC-MS profiling of diurnal variations in transgenic Arabidopsis seedlings RV 86-5 carrying modified inducible ubiquitin that prevents protein degradation via the UPS. The results present evidence that an intricate balance between the UPS and cytokinin modulates the growth response output of cytokinin signaling. On the proteome level, an LC-MS profiling identified >4,000 proteins, 61 of which were previously identified in response to proteasome inhibition.
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Interakce rostlin s pathogeny: význam proteasomu a cytoskeletu
Zelená, Pavla
Modification of substrate proteins by ubiquitin is one of the major regulatory events in eukaryotic cells, and plants use this modification to react to exogenous and endogenous cues. Mounting evidence indicates that the ubiquitin-proteasome system is also a key component in response to biotic stressors. This thesis entitled "Plant-pathogen interactions: The role of proteasome and cytoskeleton" reviews the role of proteasome in plant signaling and briefly summarizes interactions between cytoskeleton and pathogen and outlines the role of cytokinin in plant-pathogen interactions. In the experimental part, proteasome-mediated signaling is probed using growth response assay, identification of proteasome substrates and confocal microscopy of cytoskeleton structures. The results present evidence that the employed methodology will be useful for plant-pathogen interaction analyses.
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Interakcia cytokinínov a giberelínov počas predlžovania hypokotylu v odpovedi na rôzne teplotné podmienky
Tarbajová, Vladimíra
This study observed the involvement of plant hormones, cytokinins during extension of the hypocotyl of Arabidopsis thaliana seedlings ecotype Col-0 in response to ambient temperature. It also observed possible coordination of phytohormones cytokinins with gibberellin pathway, using pentuple della mutant lines background ecotype Ler-0 exposing to elevated temperature. Attention was also paid to regulation of extension growth on the transcriptional level using single and multiple pif mutant lines on a background of the ecotype Col-0. The exogenous application of cytokinin (tZ) demonstrated that elevated levels of cytokinins stimulate the extension growth of the hypocotyl under conditions of optimum temperature (20 ° C). In contrast, the trans-zeatin treated wild type of Arabidopsis thaliana showed inhibition of growth of the hypocotyl under conditions of high ambient temperature (29 ° C). Using a gibberellins´ biosynthesis inhibitor, paclobutrazol, some modulation of hypocotyl elongation thru cytokinins was found in response to the optimal and increased ambient temperature.
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Cytokinines and their role in plant cell division, with accent on G2/M transition
Prášilová, Jana ; Ševčíková, Hana (advisor) ; Bíšová, Kateřina (referee)
The eukaryotic cell cycle is well understood mainly in yeasts and animals. Basic regulatory mechanisms, with cyclin-dependent kinases (CDKs) playing crucial roles, are similar in all eukaryotes including plants. CDKs operate mainly at the key cell cycle checkpoints, G1/S and G2/M. Phosphorylation and dephosphorylation of CDKs by kinases and phosphatases have both negative and positive effect. Negative regulator at the G2/M transition is WEE1 kinase which phosphorylates conserved amino acid residues T14 and Y15 of CDK. Phosphatase CDC25 removes this inhibitory phosphate in yeasts and animals and forces cells into mitosis. Plant cell cycle exhibits remarkable differences. Importantly, it is controlled by phytohormones, and some key points of regulation remain obscure - a functional plant homologue of yeast CDC25 phosphatase has not been found in plants yet though Y15 inhibitory phosphorylation by WEE1 kinase blocks mitosis entry in plants as well. Thus, the regulatory mechanism of G2/M transition in plant cells is still to be found. Phytohormones play a key role, not only in the plant cell cycle, but in whole plant development. Interplay between the two groups of phytohormones: auxins and cytokinins, is crucial. Especially cytokinins significantly influence the regulation of G2/M checkpoint. It is...
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