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The role of phytohormones in the root system response to environmental conditions
Vávrová, Barbora ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
During their life cycle, plants form several important anatomical structures in roots, which are crucial for the proper function of the root system and for survival of plant organisms in variable environmental conditions. These structures enable plants to adapt to various stress factors of the environment. Among them, apoplastic barriers are very important. They are formed by cells of the endodermis and exodermis. These cell layers develop Casparian bands and suberin lamellae, modifications of cell walls, that block the apoplastic pathway and are necessary for selective nutrient uptake. Another structure is aerenchyma, a tissue containing many intercellular spaces, which is primarily associated with growth in flooded soils. Development of these structural adaptations is associated with the abscisic acid (ABA) and ethylene. These phytohormones are known mainly for their involvement in stress responses but they are also important in many developmental processes. Work published so far have shown that ABA stimulates deposition of suberin lamellae in the endodermis in unfavourable conditions. Ethylene on the other hand suppresses the deposition of suberin and can even trigger a degradation of previously developed suberin lamellae. In many cases ethylene plays a crucial regulatory role in development of...
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Response to repeated exposure to selected abiotic stress factors in two subspecies of olive
Skřivánek, Jakub ; Konrádová, Hana (advisor) ; Prášil, Ilja (referee)
Olive tree (Olea europaea L.) is one of the world's oldest domesticated crops, a long-living tree capable to of withstand periods of high temperatures with limited water supply, deteriorated soil conditions, but also exposure to freezing temperatures during winters. The work is focused on the characterization of stress responses of olives to selected stress factors (drought, salinity, cold) at the level of antioxidant systems and aims to answer the question whether the nature of these responses changes due to repeated exposure to the stress factor. In many plants, an important component of the stress response is the adaptation of carbohydrate balance, including changes in the total carbohydrate content as well as in their spectrum. Due to the potential of soluble carbohydrates to quench free radicals and due to the diversity of the olive carbohydrate spectrum, special attention has been paid to the study of accumulation of individual groups of carbohydrates with protective potential. We have optimized experimental in vitro cultivation conditions for two subspecies of olive tree - domesticated (Picual cultivar) and wild one (ssp. laperrinei). It was impossible to find conditions ensuring satisfactory growth of the photoautotrophic culture. In experiments simulating the water shortage by adding PEG...
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Flexibility of cyclitol metabolism as a component of effective plant defense against water scarcity
Skulníková, Barbora ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
This bachelor thesis is focused on plant defence mechanisms against drought stress and salinity stress associated with the production of compatible solutes, while attention is paid to the accumulation of cyclic sugar alcohols, myo-inositol and its methylated derivatives. It describes the occurrence of these substances, their biosynthesis and function in plants. Another part of this thesis focuses on the crystalline ice plant (Mesembranthemum crystallinum), which is an important producer of these substances and serves as a model used to study the stress response in plants. It describes its life cycle and especially the mechanisms that makes it resistant to drought stress and salinity. The last chapter is dedicated to the knowledge gained through the study of transgenic plants, which were prepared using genes from crystalline ice plant and other stress tolerant plants.
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The effect of meta-topolin application on Norway spruce somatic embryogenesis
Štěpánová, Nikola ; Konrádová, Hana (advisor) ; Eliášová, Kateřina (referee)
Somatic embryogenesis represents one of the possible methods of vegetative propagation in conifers, especially when traditional propagation ways fail. Several persistent problems prevent the wider use of this technology on a large scale (e.g. low number of high-quality somatic embryos (SE), limited stability of embryogenic capacity of cultures and many others), and even in relatively well experimentally mapped species. In order to contribute to the elimination of some weak points associated with this method, I studied the effect of change in the applied aromatic cytokinins during proliferation. I replaced usually used 6-benzylaminopurine (BAP) with its hydroxylated derivative - meta-topolin (mT). Literature data indicate that this substitution might represent a promising change that could have solve some of problems, e.g. insufficient number of somatic embryos formed or common problem with aging of embryogenic cultures. I worked with a stable, well-growing embryogenic line of Norway spruce (Picea abies (L.) Karst.) derived by our team (line C). I performed the detailed description of the line C development with the conclusion that it showed good embryogenic capacity along with a number of other characteristics common to the lines that were used as model ones in the past. For this reason, it is very...
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Potassium in plant osmoregulation
Kholová, Kateřina ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Potassium is very mobile in plants and is transported across membranes using transporters and channels. It is present in the ionic form K+ in plants. Also, in the form of this ion, K+ is taken up by plants from the soil solution. The uptake is mediated by the transporter HAK5 and by the channel AKT1. The transfer of K+ to the xylem is provided by the channel SKOR and the transporter KUP7. The role of potassium as an osmotically active element is crucial. K+ helps to regulate the amount of water in the cells and thus to maintain the turgor. Turgor is important for maintaining the shape of the plant cells and for its growth. Stomatal guard cells are used as a model system for describing processes related to the K+ osmotic function. Movement of K+ is involved in the regulation of opening and closing of stomata on the principle of turgor changes. Transport of K+ into guard cells is provided by channels KAT1, KAT2, AKT1 and AKT2. On the contrary, K+ release is mediated by the channel GORK on the plasma membrane and TPK1 on the tonoplast. K+ supports also the transport of assimilates in the phloem, where the channel AKT2 plays a role. The osmotic functions of K+ are the main topic of this bachelor thesis, which summarizes current knowledge about transport mechanisms necessary for the function of K+ as osmotically...
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Effect of exodermis differentiation on nutrient uptake localization in root
Janoušková, Jana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Plants are able to cope with changing environmental conditions or withstand its adverse effects due to their plastic development. One way to adapt to fluctuating amounts of nutrients and water in the environment or the presence of toxic substances is to regulate the movement of substances between the plant and the environment. Beside other, this regulation is also possible at the level of the root system, by the formation of apoplastic barriers endodermis and exodermis. Some species posses endodermis only, in others exodermis in hypodrermal layers of the root can be found. These barriers differentiate in three stages and prevent free movement of coumpounds though apoplast. The transport to the symplast is the key point of regulating the uptake of substances into the plant and the endodermis is the fundamental structure. The presence of exodermis, however, affects the apoplast permeability of the surface root layers and can therefore influence the involvement of the primary cortex cells in the uptake of substances from the environment. In this work the impact of phosphate deficiency on the formation of apoplastic barriers was studied focusing on exodermis and the effect of its differentiation on the occurrence of membrane transporters and involvement of primary cortex cells in the uptake of...
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Mechanisms of resistance of plants from the genus Coffea to abiotic stresses
Skřivánek, Jakub ; Konrádová, Hana (advisor) ; Tylová, Edita (referee)
The genus Coffea is so specific by its distribution, requirements for environmental conditions and economic importance for humans that it is increasingly being studied as a model plant material. The thesis in the form of literary research is worked out in the context of the emerging climatic changes in order to give a comprehensive overview of the physiological responses of plants of the genus Coffea to three abiotic stresses - heat, cold and drought. The partial goal was to compare the resistance to these stresses of two economically significant species - Coffea arabica and Coffea canephora. We cannot generally say which species is more resilient, it always depends on a particular stress. Essential parts of the reaction to these stresses have proved to be carbohydrate accumulation and content dynamics. Key words: carbohydrates, climate change, Coffea, drought, extreme temperatures, stress
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Potassium deficiency in plants - signs and responses
Štočková, Hana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Plants receive K+ mainly from the soil through the root system. In soil, K+ occurs primarily in minerals such as mica and potassium feldspar. The availability of K+ for plant uptake depends on the form in which K+ occurs in soil. There are forms directly available, slowly available, and unavailable for plant and the transition of K+ between these pools may occur. In plant, K+ is very mobile and it occurs in high amount in cells. It is the most prominent cytoplasmic cation. It affects high number of metabolic processes, including photosynthesis, osmoregulation, and activation of enzymes. K+ shortage can cause changes in plant morphology, anatomy and metabolism. K+ deficiency can be manifested by leaf deformation, decreased leaf area, necrosis, short internodes, reduced rate of photosynthesis, etc. K+ deficient plant is also more vulnerable to pathogens and its resistance to abiotic stress factors such as drought, low temperatures, or salinity is decreased. Deficiency of K+ reduces the biomass and overall yield in agricultural crops, so K+ fertilizers, both soil and foliar, are needed. The thesis focuses on the manifestations of K+ deficiency in plants and summarizes the recent findings on mechanisms of K+ deficiency perception and signal pathways leading to the response to this deficiency. Key...
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Physiological mechanisms of abiotic stress tolerance in Sorghum bicolor
Kratochvíl, Jan ; Konrádová, Hana (advisor) ; Lhotáková, Zuzana (referee)
Current agriculture is facing a serious challenge of decreasing precipitation and irregular occurrence of drought periods including their unfavorable distribution during the vegetation season. This leads to growing interest in planting highly drought-resistant crops like sorghum. In comparison with other crops, sorghum excels in low water demand, though exhibits high susceptibility to low temperatures, which hampers its spread to new regions. Surprisingly, there is not enough information about the nature of sorghum's reaction to cold exposure. The aim of this diploma thesis was to describe reactions of young sorghum plants exposed to cold stress, low water availability and their combination and to verify the possibility of plant hardening through previous low-stress load. The special focus was paid to changes in carbohydrate metabolism, which plays generally very important role in plant defense reactions. The other analyzed physiological traits were leaf tissue osmotic potential, proline content and basic morphometric characteristics. Experimental design consisted of pot experiments conducted in growth chambers and the experiments performed under controlled conditions in vitro, using two sorghum genotypes "Ruzrok" and "01Z1800012". Both genotypes exhibited similar response to stress treatment....
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