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Dissecting the effects of salicylic acid on redox balance in plant cells using biochemical and fluorescent imaging techniques
Růžičková, Gabriela ; Burketová, Lenka (advisor) ; Janda, Martin (referee)
Topic of bachelor thesis is plant immunity, specifically it focuses on salicylic acid, reactive oxygen species, it also analyses hox salicylic acid effects formation of reactive oxygen species and which proteins are involved in this biosynthesis. Also in this thesis is described basic methods for measuring of reactive oxygen species, what are advantages, disadvantages, how they work and what they can be used for. Salicylic acid is one of phytohormones involved in immune reaction in plant defence, this thesis is describing salicylic acid signalling, associated proteins and overall effect on plant. Reactive oxygen species have wide framework of action in organisms, they can be called double-edged sword, they can help plant, but also, they can harm depending on their concentration and regulation of their forming, the problem of their quenching is also described in this thesis - their formation, antioxidants, effect on plant immunity. Chapter about measuring methods is divide into three parts - fluorescence methods, chemiluminescence methods and spectrophotometric (histochemical) methods. Key words: salicylic acid, reactive oxygen species, plant immunity, plant stress, phytohormones
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The Role of selected exocyst subunits in response of plants to pathogen
Sabol, Peter ; Kulich, Ivan (advisor) ; Burketová, Lenka (referee) ; Dagdas, Yasin (referee)
In the recent years, there has been a growing number of publications indicating at the involvement of plant secretory pathway in defense against phytopathogens. Specifically, roles of plant exocyst complex have been explored in deeper detail in current research. Yet, exactly how exocyst- mediated exocytosis contributes to secretion of antimicrobials and cell wall-based defense remains unclear. In the presented Dissertation, I provide both experimental evidence and devise further hypotheses on selected exocyst's subunits in plant immune reactions. Particularly, I show that EXO70B1 exocyst subunit interacts with immunity-related RIN4 protein. Cleavage of RIN4 by AvrRpt2 Pseudomonas syringae effector protease releases both RIN4 fragments and EXO70B1 from the plasma membrane when transiently expressed in Nicotiana benthamiana leaves. I speculate on how this might have an implication in regulation of polarized callose deposition. In a co-authored opinion paper, we also hypothesize that EXO70B1-mediated autophagic degradation of TN2 resistance protein prevents its hyperactivation and lesion mimic phenotype development. In addition, in collaboration with my colleagues, I present data on EXO70H4's engagement in PMR4 callose synthase secretion, required for silica deposition. Representing a possible...
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Secretory pathway of plants in pathogene defence
Sabol, Peter ; Kulich, Ivan (advisor) ; Burketová, Lenka (referee)
Plants are sessile organisms that have to cope with the changes of their ambient environment. These changes include abiotic disturbances and stresses as well as biotic interactions with other organisms. In many of the biotic interactions, plant cells are hurt or damaged by various bacterial and fungal pathogens. Moreover, plants lack mobile immune cells, which would otherwise render them susceptible to most of these pathogens. Plants have, however, developed other mechanisms for suppressing the infection. Activating the components of the secretory pathway during resistance response is crucial step for suppressing the penetration and growth of pathogens. Fungal pathogens, such as powdery mildews, usually attempt to penetrate the cell wall in order to gain the access to protoplast providing nutrients and to exchange their virulence factors. On the other hand, pathogenic bacteria inhabit extracellular spaces of plant tissues. In both cases, however, the deposition of papilla into the plant cell wall was observed. Papilla thus seems to be the common defence mechanism. There is an increasing evidence confirming the indispensable role of polarized secretion in formation of papilla. Recently, SNARE proteins participating in papilla-associated defence have been described. PEN1 and SNAP33 syntaxins are of...
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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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Secretion and autophagy in plant defence against microbes
Dobešová, Karolína ; Žárský, Viktor (advisor) ; Burketová, Lenka (referee)
Plants are sessile organisms and when attacked by microbes, they cannot easily run away. For this reason, they have developed sophisticated defensive mechanisms, that allow them to defend themselves. Since plants, unlike mammals, do not have any special immune cells, their defense takes place in each cell separately. The key moment during a microbial infection is the recognition of the microbe by the plant through its released molecular patterns (mostly proteins) associated with microbes (MAMPs). MAMPs trigger signaling cascades that lead to the secretion of antimicrobial compounds to the site of an attack. The process of autophagy is also important in the defense against microbes, which not only maintains a cellular homeostasis and controls the level of phytohormones and defense proteins in the plant cytoplasm, but also participates in the secretory activity of the cell. Recent analyzes of plant secretome have shown that plants secrete many proteins (including defensive ones) independently of the signal peptide and compartments of a conventional secretion. During exocytosis a vesicle fuses with the cytoplasmic membrane. The octameric protein complex exocyst and SNARE proteins take part in this process. The exocyst complex is highly diversified in plants - especially it's EXO70 subunit, which is...
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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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Connection between Unfolded Protein Response (UPR) and plant immunity
Kapr, Jan ; Burketová, Lenka (advisor) ; Vosolsobě, Stanislav (referee)
This bachelor thesis is concerned with the specific pathway in a response to endoplasmic reticulum stress in plant cells - the Unfolded Protein Response (UPR) and its role in plant immunity signalling. The work summarizes the main recent knowledges of molecular components of plant immunity and response to plant pathogens, focusing on important molecules that are also connected to UPR. The role of salicylic acid as a molecule on a crossroad between UPR signalling pathways and local and systemic resistence, is highlighted in this work. Recently, the phospholipids have also been shown to be important component of signaling pathways in response to biotic stress in plants and their role is also mentioned.
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Role of phytohormones in the interaction of plant pathogens Pseudomonas syringae and Leptosphaeria maculans with their host
Leontovyčová, Hana ; Burketová, Lenka (advisor) ; Ryšlavá, Helena (referee) ; Sedlářová, Michaela (referee)
Phytohormones are small molecules that regulate almost all aspects of plant life including defence reactions. Plant defence and immunity are mainly regulated by two hormones - salicylic acid (SA) and jasmonic acid (JA). Other hormones such as auxins, cytokinins brassinosteroids or gibberellins modulate plant immunity to lesser extent. It has been described that plant pathogens are able to interfere with plant hormone signalling to overcome plant defence. Some pathogens are able to produce plant hormones themselves. This thesis is focused on plant hormone signalling involved in plant immunity both from the plant side and pathogen side and possible hormonal crosstalk in this interaction. The first part is focused on salicylic acid signalling connected with plant actin cytoskeleton roles in plant immunity. It has been described that desintegration of actin cytoskeleton leads to increased plant susceptibility to bacteria. However, it has been also shown that pharmacological desintegration of actin filaments induces transcription of salicylic acid responsive genes PR1 (Pathogenesis related 1) and ICS1 (Isochorismate synthase 1). In this thesis we have investigated this inconsistency using actin depolymerizing drugs latrunculin B, cytochalasin E and jasplakinolide and two different pathosystems:...
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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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