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Autophagy in plant abiotic stress
Kosťová, Natálie ; Hála, Michal (advisor) ; Martinec, Jan (referee)
Autophagy is a cellular mechanism when cell gets rid of its damaged or unwanted components. These are wrapped into a double membrane and creates so-called autophagosome, which is transported to the vacuole, where its contents are degraded or recycled. Autophagy runs essentially through whole life of the plant, but if it is necessary, for example in response to stressful conditions, it is significantly intensified. It is relatively complexly regulated mechanism, which, especially in plants, still has not been completely described. Autophagy plays an important role under the influence of stress conditions. Especially, the effects of abiotic stress play an important role in plant life. Plants are immobile organisms so they must therefore develop mechanisms to enable them to survive in adverse conditions. In response to different types of stress, we can observe different roles in the involvement of autophagy, whether it is disposal of poorly folded proteins, remobilization of nutrients or antioxidant mechanism. Autophagy is also especially important for the process of stress memory and regulation.
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Specific roles of Argonaute family proteins in Arabidopsis thaliana
Teznerová, Kateřina ; Fischer, Lukáš (advisor) ; Hála, Michal (referee)
Argonaut proteins are RNA binding proteins with RNase activity. They can bind short non-coding RNAs, which are usually 21-24 nt in length. These small RNAs are formed in plants from double-stranded RNAs and are involved in the regulation of gene expression, in the protection of the plant against viruses, transposons, or other invasive genetic elements, and affect the state of chromatin. Using small RNAs, Argonaut proteins participate in a mechanism called RNA interference, a complex process used to regulate gene expression, at the transcriptional or post-transcriptional level. In the plant species Arabidopsis thaliana, the Argonaut family of proteins has 10 genes, while in other plant species they have their functional homologues (orthologs). Individual proteins differ in their preference for different types of small RNAs depending on their length, the 5 'terminal nucleotide and the way in which the source double-stranded RNA is formed. At the same time, the involvement of individual types of Argonaut in the partial processes of RNA interference and in connection with their cellular localization also differs. This work is focused on the interaction of small RNAs with Argonaut proteins, describes the processes of their functioning and further deals with individual paralogs of Argonaut proteins in...
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Plant responses to low temperatures, resistance and damage
Kabilková, Eva ; Prášil, Ilja (advisor) ; Hála, Michal (referee)
Plants can encounter many stressors throughout their lives, including low temperatures. This work characterizes the limits of extreme temperatures that have an effect on plants; cold (temperatures ranging from 0 ř C to 15 ř C) and frost (temperatures below 0 ř C accompanied by ice formation in plant tissues). Consequences of plant damage caused by extreme temperatures are also given, as well as the most important plant resistance and defense mechanisms in response to these stressors, especially at the cellular level. These are temperature responding signalling transduction pathways leading to the activation of stress genes and some phytohormones (abscisic acid, salicylic acid, jasmonates), as well as the accumulation of stress proteins (e.g. anti-freezing proteins, dehydrins). At the same time, some of the impacts of climate change, including global warming, on selected plants species are mentioned. Key words: stress, plants resistance, tolerance, low temperature, cold, frost, damage to plants
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Transporters KT/HAK/KUP - role in plant development and response to environmental conditions
Doležalová, Barbora ; Tylová, Edita (advisor) ; Hála, Michal (referee)
Potassium is an essential element, which is important in many plant processes. It functions as a major osmotic and is involved in the regulation of turgor during cell growth or stomatal movements. It is also important for maintaining membrane potencial. In plants, potassium transporters from the KT/HAK/KUP family are involved in the transport of K+ . Some of them are important in the uptake of K+ from the enviroment (HAK5, KUP7), others in regulation of cell turgor (KUP2, KUP6, KUP8). In Arabidopsis thaliana, less characterized KT/HAK/KUP transporters include KUP5 and KUP9, which I studied in this diploma thesis. In this diploma thesis, I analyzed the growth phenotype of kup5 mutant plants. The results show that kup5 mutant plants are not more sensitive to K+ deficiency than wild-type plants, therefore KUP5 is probably not involved in the K+ uptake from the enviroment. Kup5 mutant plants were larger than wild-type plants, had larger root and hypocotyl cells as well as longer root meristematic zone. This growth phenotype suggests that KUP5 is involved in the regulation of cell growth, probably through turgor regulation. Using the pKUP5::KUP5-GFP construct, the KUP5 protein was localized in the ER, but this localization needs further verification. Using the pKUP5:GUS construct, KUP5 expression was...
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The Role of Lipids and Lipid Metabolizing Enzymes in Plant Autophagy
Krupař, Pavel ; Martinec, Jan (advisor) ; Hála, Michal (referee)
Plant autophagy is a crucial evolutionary conserved process for recycling cytoplasmic material under stress conditions or during development. The autophagic pathway is negatively regulated by TOR kinase, a versatile molecule modulating a wide range of cellular processes. In mammals, TOR kinase may be activated by phosphatidic acid, a vital signalling lipid. This thesis aims to prove the possible involvement of phospholipids in plant autophagy. I analysed the rate of primary root inhibition in knock-out mutants coding phospholipases in A. thaliana with induced autophagy, measured activity of lipid metabolising enzymes in wild type and atg10 mutant and observed autophagosome formation in selected mutants. Autophagosomes were labelled by fluorescent protein in vivo and by indirect immunolabelling in fixed samples. Using advanced stereological approach, I optimized a method for obtaining an unbiased estimate of autophagosome number in plant root cells.
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Actin and the ARP 2/3 complex in the nucleus
Němcová, Barbora ; Bellinvia, Erica (advisor) ; Hála, Michal (referee)
The eukaryotic actin cytoskeleton is required for numerous cellular processes, including cell shape, development and movement, gene expression and signal transduction, and response to biotic and abiotic stress. Actin constitutes a wide family of proteins that are major components of the cytoskeleton. Actin is one of the most abundant proteins in living organisms. Actin has essential functions both in the cytoplasm and in the nucleus, where it has been linked to key nuclear processes. Recent studies have shown that actin is actively transported from the cytoplasm to the nucleus, where it regulates transcriptional aktivity, regulates RNA polymerases, is involved in chromatin remodeling and repair damaged DNA. The presence of typical actin filaments in the nucleus has not been demonstrated directly.but nuclear actin occurs in many forms such as actin rods, short actin polymers, actin monomers, or actin complexes with profilin or cofilin. Most eukaryotic cells also contain at least eleven actin-related proteins (ARPs). Although many ARPs are cytoskeletal, recent biochemical and genetic work has demonstrated that some ARPs function largely or entirely in the nucleus. Nuclear ARPs are recognized as novel key regulators of genome function, and affect not only the remodeling of chromatin but also the...
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Function of the AtKUP5 transporter in Arabidopsis thaliana
Štočková, Hana ; Tylová, Edita (advisor) ; Hála, Michal (referee)
Potassium is one of the essential elements necessary for plant growth. It is involved in many plant processes, such as osmoregulation, enzymes activaton, etc. These functions are very often closely related to its transport in the cell and the whole plant. Although potassium is abundant in earth's crust, the mount of plant-available form is often insufficient. Potassium deficiency manifests itself on many levels and also contributes to the reduction of yield and quality of agricultural crops. There are many of potassium-transporting proteins in the plant. One of the important families of potassium transporters is the KT/HAK/KUP family. This family includes, among others, the high-affinity transporter HAK5, which is key for the uptake of potassium from the environment with low-potassium availability. One of the not very characterized transporters from the KT/HAK/KUP family is the KUP5 transporter, which I deal with in my diploma thesis. The aim of this work is to analyze the phenotypic manifestations of kup5 T-DNA insertion mutants and to characterize the functions of the transporter KUP5 in Arabidopsis thaliana plants. I analyzed the growth of kup5 insertion mutants in various environmental conditions and performed plant transformation to determine the localization of the KUP5 transporter in the...
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Stomata opening and closure regulation in respect to osmotic stress
Hofírková, Miroslava ; Hála, Michal (advisor) ; Lhotáková, Zuzana (referee)
Stomata are structures located in higher plants' epidermis and they regulate mainly CO2 intake and transpiration. The stomata are important for plants' protection against excessive water loss during osmotic stress. This thesis is a literary research summarizing stomatal movements regulation during osmotic stress. The main part of the thesis is focused on stomatal closure with the help of ABA under water deficiency conditions. There are the ABA synthesis, transport and its impact on stomata described in individual chapters. The ABA early signalling pathway and an ionic channel regulation are described in detail on the basis of the published data. The second part of the thesis is about second messengers produced by ABA and their impact on stomatal movement regulation. The special attention is paid to hydrogen peroxide and nitric oxide and their contribution to stomatal closure. The last part is about passive (hydraulic) stomatal closure. Keywords: plants, stomata, osmotic stress, ABA, stomatal movements
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Cuticle, its formation and importance in resistance of plants to abiotic stress
Litkeiová, Veronika ; Hála, Michal (advisor) ; Tylová, Edita (referee)
Plants are daily exposed to stress, biotic or abiotic. Both of these types can be divided into several subgroups. This work is focused on plant cuticle, its formation and function in respect to abiotic stress resistance. The main factors, mentioned in this work, are drought, heat, UV radiation, excessive salinity or ozone exposure. The individual chapters focus on the composition, biosynthesis and changes in the build-up construction caused by certain types of stressors. A significant part is also devoted to cutin and cuticular waxes, which play an important role in plant protection and whose structure is also affected by abiotic stress. Phytohormones, especially abscisis acid, which had its application here, are also not omitted. In the final phase of the thesis, cuticular mutants are mentioned in connection with abiotic stress types illustrating the role and the importance of the cuticle layer. Key words: plants, cuticle, osmotic stress, abscisic acid, cutin, waxes
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Plant tomosyns and their role in secretion
Dejová, Lilly ; Hála, Michal (advisor) ; Fendrych, Matyáš (referee)
Tomosyn is a protein belonging to the Lgl family and conserved across the animal and plant kingdom. Tomosyn is composed of N-terminal domain containing WD40 motif and Cterminal domain, where the R-SNARE motif is located at the end of the C-terminal domain. This motif is classified as homologous to R-SNARE motif of synaptobrevine, which is a protein located on the surface of the vesicles and participating in the formation of SNARE complex and subsequent fusion of the vesicles with the plasma membrane. Thus the role of this tomosyn is mainly the regulation of exocytosis. Apart from the animal tomosyn, its yeast homolog Sro7/Sro77 is also examined, however during the evolution it has lost its R-SNARE motif and therefore the plant tomosyns remain unexplored. The aim of this diploma thesis was to characterize both of the plant tomosyns: AtTYN1 and AtTYN2 in Arabidopsis thaliana plant. The experimental thesis included the bioinformatic analysis, the DNA construct creation, a search for interactors by yeast two-hybrid system and monitoring the localization using the confocal microscope. The bioinformatic analysis results, including the creation of phylogenetic tree, not only revealed the conservation of tomosyns across the different classes, but also the division of both tomosyns into different clusters. There was...
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