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AHL genes in plant development
Škrabálková, Eliška ; Širl, Marek (advisor) ; Ortmannová, Jitka (referee)
Plant development is a complex process where different factors come into play. The expression of certain genes, which determine basic plant structure and its signaling pathways, is also of great importance. The AHL gene family, which in case of Arabidopsis thaliana includes 29 members, is one of those determinators that have an impact on plant development on several levels. As far as structure is concerned, the AHL proteins are typically composed of two parts - the DNA-bonding AT-hook motif and PPC domain, which defines nuclear localisation and eventually enables oligomerisation. In terms of phylogenetics, the AHL proteins are divided into clades A and B on the basis of number and type of these domains. When it comes to affecting plant development, these nuclear proteins are capable of bonding with the corresponding DNA, and in cooperation with other factors influencing gene expression. In the plant body the AHL proteins are involved in root and floral organogenesis and also cooperate with a number of signaling pathways of phytohormones, such as auxins, gibberellins, brassinosteroids or senescence hormones. Moreover, they take part in photomorphogenesis or control systematic immune responses of the plant. Keywords: AHL, AT-hook, PPC domain, nuclear protein, Arabidopsis thaliana
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Study of the interaction of proteins involved in the exocytosis in the plant defense against pathogens
Ortmannová, Jitka ; Pečenková, Tamara (advisor) ; Burketová, Lenka (referee)
Plant cells are mostly immobile, therefore it is crucial for them to distinguish a direction of the signals coming into the cell and on the other hand they have to precisely target their own signals. To achieve this communication, plant cells use endomembrane system and secretory vesicles, which are recruited to the specific membrane domains. This ability is important for the plant defense against pathogenic microorganisms and it even forms a part of the innate plant immunity. Two complexes, the exocyst and SNARE, play a prominent role in the process of polarized secretion. In this work, we focused on a possible interaction between these two complexes in preinvasive defense and particularly, we studied the exocyst subunit EXO70B2 and SNARE protein SYP121. We obtained double mutant plants of EXO70B2 and SYP121 by utilizing the reverse genetics approach. These mutant plants did not show any obvious phenotype under standard conditions in comparison with Wt plants. However, we observed marked defects of secretory pathway in double mutant exo70B2/syp121 after infection by pathogenic fungi Blumeria graminis f. sp. hordei. Using histochemical staining, we described problems with the deposition of defensive papilla and secretion of haustorial encasement. We prove that these defects are not connected with...
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Interaction of Plant Protein Complex Exocyst with Proteins Involved in Plant Immunity
Ortmannová, Jitka ; Žárský, Viktor (advisor) ; Burketová, Lenka (referee) ; Ovečka, Miroslav (referee)
Plants have an artillery to defend themselves. The plant surface is protected by water- resistant cuticle and mechanically strong cell wall. Then each plant cell has tools to recognize and to answer to a pathogen threat. In an extreme case, the answer is programmed cell death. Plant immunity is a complex process integrating these passive and active mechanisms in an effort to overstay a pathogen attack. When the plant cell is attacked by a pathogen, the metabolic resources are redirected towards immunity reaction which results in growth restriction. Both the immunity reaction and the growth are dependent on the efficient polarized secretion of various cargoes. Exocyst complex mediates tethering of a secretory vesicle with a target membrane and SNARE complex orchestrates the subsequent steps of vesicle docking and fusion. Exocyst and SNAREs are regulated by various proteins. In my work, I focused on identifying the exocyst interaction partners in plant immunity. In cooperation with my colleagues, we found the direct association between Qa-SNARE SYP121 involved in plant penetration resistance and EXO70B2 exocyst subunit. Moreover, we confirmed the relevance of their interaction for the formation of epidermal defensive structures, papillae and haustorial encasements in plant defence against non-adapted...
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Interaction of Plant Protein Complex Exocyst with Proteins Involved in Plant Immunity
Ortmannová, Jitka ; Žárský, Viktor (advisor) ; Burketová, Lenka (referee) ; Ovečka, Miroslav (referee)
Plants have an artillery to defend themselves. The plant surface is protected by water- resistant cuticle and mechanically strong cell wall. Then each plant cell has tools to recognize and to answer to a pathogen threat. In an extreme case, the answer is programmed cell death. Plant immunity is a complex process integrating these passive and active mechanisms in an effort to overstay a pathogen attack. When the plant cell is attacked by a pathogen, the metabolic resources are redirected towards immunity reaction which results in growth restriction. Both the immunity reaction and the growth are dependent on the efficient polarized secretion of various cargoes. Exocyst complex mediates tethering of a secretory vesicle with a target membrane and SNARE complex orchestrates the subsequent steps of vesicle docking and fusion. Exocyst and SNAREs are regulated by various proteins. In my work, I focused on identifying the exocyst interaction partners in plant immunity. In cooperation with my colleagues, we found the direct association between Qa-SNARE SYP121 involved in plant penetration resistance and EXO70B2 exocyst subunit. Moreover, we confirmed the relevance of their interaction for the formation of epidermal defensive structures, papillae and haustorial encasements in plant defence against non-adapted...
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AHL genes in plant development
Škrabálková, Eliška ; Širl, Marek (advisor) ; Ortmannová, Jitka (referee)
Plant development is a complex process where different factors come into play. The expression of certain genes, which determine basic plant structure and its signaling pathways, is also of great importance. The AHL gene family, which in case of Arabidopsis thaliana includes 29 members, is one of those determinators that have an impact on plant development on several levels. As far as structure is concerned, the AHL proteins are typically composed of two parts - the DNA-bonding AT-hook motif and PPC domain, which defines nuclear localisation and eventually enables oligomerisation. In terms of phylogenetics, the AHL proteins are divided into clades A and B on the basis of number and type of these domains. When it comes to affecting plant development, these nuclear proteins are capable of bonding with the corresponding DNA, and in cooperation with other factors influencing gene expression. In the plant body the AHL proteins are involved in root and floral organogenesis and also cooperate with a number of signaling pathways of phytohormones, such as auxins, gibberellins, brassinosteroids or senescence hormones. Moreover, they take part in photomorphogenesis or control systematic immune responses of the plant. Keywords: AHL, AT-hook, PPC domain, nuclear protein, Arabidopsis thaliana
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Study of the interaction of proteins involved in the exocytosis in the plant defense against pathogens
Ortmannová, Jitka ; Pečenková, Tamara (advisor) ; Burketová, Lenka (referee)
Plant cells are mostly immobile, therefore it is crucial for them to distinguish a direction of the signals coming into the cell and on the other hand they have to precisely target their own signals. To achieve this communication, plant cells use endomembrane system and secretory vesicles, which are recruited to the specific membrane domains. This ability is important for the plant defense against pathogenic microorganisms and it even forms a part of the innate plant immunity. Two complexes, the exocyst and SNARE, play a prominent role in the process of polarized secretion. In this work, we focused on a possible interaction between these two complexes in preinvasive defense and particularly, we studied the exocyst subunit EXO70B2 and SNARE protein SYP121. We obtained double mutant plants of EXO70B2 and SYP121 by utilizing the reverse genetics approach. These mutant plants did not show any obvious phenotype under standard conditions in comparison with Wt plants. However, we observed marked defects of secretory pathway in double mutant exo70B2/syp121 after infection by pathogenic fungi Blumeria graminis f. sp. hordei. Using histochemical staining, we described problems with the deposition of defensive papilla and secretion of haustorial encasement. We prove that these defects are not connected with...
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Advanced methods of endocytosis and exocytosis visualisation on plant cell membrane
Ortmannová, Jitka ; Fendrych, Matyáš (advisor) ; Krtková, Jana (referee)
Endocytosis and exocytosis participate in developmental program of plants.The ability to target exocytic vesicles to particular domains of plasma membrane is crucial for polarization, growth and development. Plasma membrane are recycled via various mechanisms of endocytosis which participates also in establishing plant cell polarity. To extend our knowledge of membrane transport it is essential to observe the activity of its components with high resolution in living cells of intact organisms in real time. Such methods belong mainly into the field of light microscopy and nanoscopy exceeding often diffraction limit (200 nm). Nanoscopic techniques like PALM, STORM, SIM, STED, offer multicoloured visualization of fluorophores and high resolution 3D reconstruction of cellular component. These methods have been used only sporadically in the field of plant biology but there should be no serious obstacles for they employment. The key words: clathrin, difraction limit, endocytosis, exocytosis, exocyst, fluorophore, plant cell, microscopy, resolution
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