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Heat-shock proteins and plant tolerance against high temperature stress
Ott, Kristián ; Hála, Michal (advisor) ; Konrádová, Hana (referee)
In context with ongoing climate change, the average temperature is still rising. This is a problem mainly for agriculture and production of groceries, because plants generally have difficulties when coping with ambient temperature higher than 40 řC. If there would be continuing trend in decrease of global food production, it could cause problems with feeding still growing world population. Organisms in general developed many mechanisms of stress adaptation. One of these evolutionary adaptions to high temperature stress is production of heat shock proteins (HSPs). HSPs are very conserved family of proteins present in both prokaryotes and eukaryotes. This thesis summarizes present knowledge about the HSPs and their function (not only) during the high temperature stress in plants, but some of the information presented in this thesis were obtained also from other organisms. The thesis starts with general introduction to the high temperature stress and how plants can sense the ambient temperature. Next is general mechanism of induction of HSPs and their classification, structure, and mechanism of action. The possibility of future use of HSPs in agriculture and medicine is opened in last chapter.
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Characterisation of Arabidopsis thaliana mutants psbo1 and psbo2
Nykles, Ondřej ; Duchoslav, Miloš (advisor) ; Hála, Michal (referee)
The PsbO protein is necessary for the function of the electron-transport chain of the thylakoid membrane in higher plants. In most of the angiosperms, including Arabidopsis thaliana, this protein has two isoforms termed as PsbO1 and PsbO2. Many authors tried to reveal the fundamental difference between the PsbO1 and PsbO2 with the help of the mutant lines which lack one of the isoforms. The problem is that the mutants in psbO isoforms do not possess the same level of PsbO as WT does. So we made psbo1isoL mutants. These lines contain only one isoform but their level of the whole PsbO is comparable to the level of the whole PsbO of WT. Results from these experiments suggest that if a psbo1isoL plant has the same amount of PsbO as WT does, there is no observable phenotype difference. Thus we were not able to identify, in the usual cultivation conditions, if there are any functional differences between PsbO1 and PsbO2 Following the above mentioned results, we would like to know conditions (if there are any) in which T-DNA insertion mutants psbo2 (respectively psbo2cr which are made with the use of the CRISPR/Cas9), which have only PsbO1 isoform, could be phenotypically distinguished from WT. With the use of usual cultivation conditions, we are unable to tell apart the psbo2 and psbo2cr from WT by the...
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The effect of phosphorylation in the regulation of Rho-GTPases
Novotná, Michaela ; Rösel, Daniel (advisor) ; Hála, Michal (referee)
This bachelor thesis is focused on regulating of the activity of the Rho GTPases. Rho GTPases are important signalling proteins that are involved in regulation of many cellular processes, for example dynamic cytoskeleton changes (especially actin fibres) associated with cell adhesion and migration, vesicle trafficking or cell cycle. The activity of the Rho GTPases is primarily regulated by other proteins affecting the presence GTP/GDP or by posttranslational modifications. This thesis is focused on a narrow section of these modifications, namely phosphorylations. Phosphorylation of the Rho GTPases affects for example their activity, localization, or degradation. Understanding the mechanism of regulation of Rho GTPase activity is important for comprehension of cellular processes. Rho GTPases are involved, for example, in tumour cell invasiveness. By studying Rho GTPases and their regulation, it is possible to better target potential treatment or even prevent the occurrence of the metastases.
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Mechanisms of natural resistance of quinoa to abiotic stresses
Cíza, Marek ; Lipavská, Helena (advisor) ; Hála, Michal (referee)
Quinoa is traditionally grown crop originating from areas adjacent to Andean Mountains in South America, where it is grown by local native population for over 5000 years. Its extraordinal resistance to abiotic stresses as salinity, drought or frost, along with quite exceptional nutritional qualities of the seed, earned it the designation "supercrop" and the year 2013 was even announced by the FAO organization as the International Year of Quinoa. The main aim of this thesis is to identify the main mechanisms responsible for quinoa resistance to frost, salinity and drought. Marginally, this work also focuses on reaction of quinoa against an attack of most common fungal pathogen and also on different sensitivity of quinoa varieties towards the lenght of photoperiods, which are two important factors in expanding the cultivation of quinoa outside the original area.
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Water use efficiency (WUE), its definition and importance in plant resistance against osmotic stress
Jedlička, Tomáš ; Hála, Michal (advisor) ; Lhotáková, Zuzana (referee)
Water is one of the main limiting factors of plant growth. Availability of water on our planet is decreasing, and if we add fast-growing human population, we have a problem growing. Scientists from all around the world, especially those from arid regions, are facing a big problem, which is an attempt to make the most efficient use of water by plants. If this problem should be solved, we need to understand the issue of Water Use Efficiency (WUE). This paper attempts to summarize the current knowledge related to the issue of WUE, mainly focused on anatomical and physiological parameters control of WUE, which is focused primarily on the issue of evapotranspiration. Another part focuses on clarifying the issue of WUE at the gene level and the related biotech opportunities. At the end of the work are discussed possibilities of increasing WUE using irrigation techniques. Key words: water use efficiency, evaporation, transpiration, stoma, stomatal density, abscisic acid, ERECTA
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Effectors of RAB GTPases and their role in plant secretion
Růžičková, Martina ; Hála, Michal (advisor) ; Motyka, Václav (referee) ; Klíma, Petr (referee)
Rab GTPases are small signaling molecules that play an important role in vesicle trafficking in eukaryotic cells. Correct signaling through small GTPases allows orchestration of vesicle transport among cellular organelles and also to the cell wall providing cell wall material for cell growth and elongation. Engagement of Rab GTPases in the regulation of endomembrane trafficking is one of the evolutionary conserved aspects of secretion regulation. The network of Rab GTPases interaction includes also various downstream effectors. One of them is the exocyst complex involved in vesicle docking at the plasma membrane. It is a complex composed of eight different subunits (Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70 and Exo84). Exocyst was discovered as Sec4p Rab GTPase effector in yeast and also data from animal models describe the Sec15 exocyst subunit as the Rab-interacting partner, but data from plants are missing. On the other hand, numerous studies identified exocyst role in tip growth of pollen tube and root hairs, seed coat formation, cell plate and cell wall formation, hypocotyl elongation, and importantly also PIN auxin efflux carriers recycling and polar auxin transport. There are two paralogues of SEC15 in the Arabidopsis genome, SEC15a and SEC15b, the previous one already shown to be...
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The role of trehalose in mycorrhizal associations
Šoch, Jan ; Ponert, Jan (advisor) ; Hála, Michal (referee)
Mycorrhizal symbiosis is a widely spread phenomenon in nature. A translocation of nutrients occurs between symbionts with disaccharide trehalose playing a key role in the process. However, this saccharide fulfils many important roles in metabolism of fungi and plants. Fungi use trehalose mainly as storage and transport saccharide. On the other hand, trehalose occurs in extremely low amounts in plants where it acts as a signal molecule. Thus it is likely that the saccharide could be used by the fungus to manipulate plant metabolism on a physical interface between symbionts. Trehalose has a similar function in many parasitic interactions. In most cases of mycorrhizal associations trehalose synthesis creates a carbon sink in mycelium which leads to saccharide transfer from the host plant to the fungus. Completely different situation occurs in the types of mycorrhizal symbiosis, where saccharides are translocated from a fungus to a plant. Some plants can utilize trehalose effectively as a sole source of energy. Consequently, the question raises - could such plants gain fungal trehalose on purpose as a source of energy and carbon? This review aims to assess and discuss the mentioned possibilities considering available literature. Key words: mycorrhiza, orchids, parazitism, saccharides, sink, symbiosis,...
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Leaf structural changes induced by tropospheric ozone.
Češpírová, Zdeňka ; Lhotáková, Zuzana (advisor) ; Hála, Michal (referee)
Tropospheric ozone is an important pollutant formed by the photochemical reactions of ultraviolet radiation and nitrogenous. Recently, its concentration in the air is increasing due to the promoting climate change and antropogenic activities, mainly because of combustion of the fossil fuels. The ozone is highly reactive molecule degrading to the reactive oxygen species having negative effects on the leaf physiological functions and structure. Ozone penetrates the leaf through the stomata, thereafter it reacts with the cells and their singular compartments. The products formed due to ozone degradation are able to cause the disintegration of plasma membranes and other oxidative damage, for example accumulation of plastoglobuli inside the chloroplasts, changes in the shape of chloroplasts, mitochondria or peroxisomes. At the macroscopic level the visible lesions, chloroses and necroses are observed. In addition, the faster senescence of leaves is observed under the effect of ozone. The main aim of present thesis is to review knowledge of the ozone-induced changes in the leaf structure beginning on the cell structure level and ending at the whole plant body level and to explain physiological mechanisms leading to these damages. Key words: ozone, oxidative stress, leaf structure, mesophyll, reactive...
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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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