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Saccharides as an integral part of plant antioxidative system
Štěpánová, Nikola ; Lipavská, Helena (advisor) ; Hála, Michal (referee)
The formation of reactive oxygen species (ROS) in plants is inevitable part of aerobic cellular metabolism, during which ROS are generated as by-products of basal metabolic pathways. ROS participate in many processes in plants. If the ROS are at normal level, they serve as signal molecules. Under stress, however, the ROS level in plants increases. High ROS accumulation can cause severe oxidative damage of cellular components, but simultaneously it activates other signal pathways controlling defence against oxidative stress. Plants protect themselves against increased level of ROS in different ways. Either they try to prevent increased level of ROS, or they try to detoxify them. Plants utilize for detoxification two efficient antioxidative systems - enzymatic and non-enzymatic ones. The main goal of this work is to put saccharides into context of plant non-enzymatic antioxidative system and summarize saccharides-based ROS scavenging mechanisms, which have been invented so far. Research on mechanisms of ROS scavenging is highly important, because oxidative damage through excessive production of ROS is considered to be significant cause of productivity losses in agricultural crops. These losses are likely to increase as a result of increased stress burden connected with expected climatic changes. Key...
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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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The physiological basis of abiotic stress tolerance in Fragaria genus plants.
Hamet, Jaromír ; Lipavská, Helena (advisor) ; Tylová, Edita (referee)
Abiotic stresses - drought, salinity or extreme temperatures - cause morphological and physiological changes, affect growth, development and plant productivity. In crops, these limitations often reduce yields up to 50%. Plants have developed various mechanisms ensuring some degree of abiotic stress tolerance, which undoubtedly include changes in carbohydrate metabolism. The nature of many defense mechanisms is not yet fully understood, moreover, most findings were obtained by studying model plants and little is known about their validity in crops. This work was therefore focused on woodland strawberry (Fragaria vesca L.) from economically important family Rosaceae. Controlled conditions and targeted exposure to stress factors was obtained through the cultivation in vitro. Strawberry plants and callus cultures were exposed to various stresses and their combinations, better reflecting the natural conditions. At various stages of stress reaction, growth characteristics, changes in the content and the spectrum of soluble carbohydrates and oxidative stress levels were monitored and compared with plants growing under optimal conditions. Abiotic stress responses of strawberry plants were very inhomogeneous, which complicated the obtaining of statistically significant results. The only significant response...
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Do tuberization and flowering share common control mechanisms ?
Stupecká, Lenka ; Lipavská, Helena (advisor) ; Fischer, Lukáš (referee)
The transition from vegetative to reproductive phase is called flowering. The right timing of flowering is essential for successful reproduction of plants. Flowering is controlled by many external and internal factors including day length or photoperiod. The photoperiod is perceived in leaves, where the mobile signal called "florigen" is produced. It is thereafter transported from the leaves to the stem apical meristem where flowering is induced. Photoperiodic regulatory pathway involves genes whose mutual interactions and gene interactions with other pathways determine timing of flowering. Tuberization of potato plants (Solanum tuberosum L.) is important morphogenetic process taking place in underground stem (stolon), where storage organs - tubers - are formed. Precise timing of tuberization is important for successful overwintering, and vegetative reproduction of potato. Onset of tuber formation is governed by external and internal conditions especially temperature, nutrient availability and photoperiod. The process is stimulated by short day conditions. Photoperiodic pathway controlling tuberization has several common components with photoperiodic pathway controlling flowering, including the participation of mobile signal - "tuberigen". Recent findings on proteins involved in photoperiodic...
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Trehalose metabolism gene manipulations and improving plant abiotic stress tolerance
Hamet, Jaromír ; Lipavská, Helena (advisor) ; Hála, Michal (referee)
In these days, genetic modifications of crops are commonly used in the fight against pests and weeds. More and more often there are also efforts to use genetic modifications to increase tolerance to abiotic stresses that affect worldwide yields much more than biotic ones. Manipulation of trehalose metabolism represents one of the frequently studied options of abiotic stress tolerance enhancement. This work summarizes current knowledge on the protective effects of trehalose in cells and describes signaling functions of trehalose and its metabolic intermediate trehalose-6-phosphate in plants. It also describes current achievements in increasing abiotic stress tolerance through genetic modifications of trehalose metabolism together with accompanying problems. Finally, the potential of this method for future exploitation is discussed.
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The effect of uranium on carbohydrate metabolism of cultivated plants.
Lábusová, Jana ; Lipavská, Helena (advisor) ; Lhotáková, Zuzana (referee)
Nowadays, the environmental pollution by heavy metals is very serious problem all around the world. Radionuclides, including uranium, are heavy metals that cause both chemical and radioactive pollution. Naturally occurring uranium is not so dangerous for living organisms. Human activities, especially uranium ore mining and use of phosphate fertilizers, have increased its concentration in the environment with consequent contamination of soil, water and air. Compared to other countries, the Czech Republic is relatively rich in deposits of uranium ore. Extensive mining results in large contaminated areas, containing not only uranium but also other heavy metals and xenobiotics that need to be removed from the environment. One way how to decontaminate soils and waters is phytoremediation. This eco-friendly and cost-effective technique exploits the ability of plants to take up, translocate, transform and sequester xenobiotics. In order to provide functional phytoremediation, it is necessary to understand the mechanisms of plant responses to stress caused by xenobiotics. Therefore in my master thesis, I focused on the impact of uranium on physiological processes of uranium-stressed plants, with the emphasis on carbohydrate metabolism and antioxidative defense mechanism. Powered by TCPDF (www.tcpdf.org)
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The effect of heavy metals on plant carbohydrate metabolism
Kofroňová, Monika ; Lipavská, Helena (advisor) ; Podlipná, Radka (referee)
Arsenic is an element which belongs to metaloids. Contamination with arsenic is a problem all over the world. Basically it is a part of Earth's crust, but with anthropogenic activities it could overspread into soil, water and air in large scale a thus it could mean health hazard. Fytoremediation is kind of environment decontamination, which is quite effective and cheap as well. Publications about arsenic and its influence on plant metabolism are mostly focused on important crop plants like rice. Rice is mostly used for experiments and questions on anatomical and morphological changes are widely being solved by these experiments, but it has only insignificant relevance for fytoremediation. There are only few publications about arsenic influence on carbohydrate metabolism, thus little is known about this problem. That is why I have decided to study this topic more deeply and get more information about carbohydrate metabolic changes under influence of arsenic and partly also under influence of mercury, because information about influence of mercury are completely lacking. My experimental material includes tobacco plant, tobacco tissue cultures and horseradish hairy roots cultures. Accumulation of starch and soluble carbohydrate spectrum and content was determined by HPLC. Furthermore arsenic influence...
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Cytokinins and plant senescence
Pokorná, Monika ; Lipavská, Helena (advisor) ; Kutík, Jaromír (referee)
Senescence is a natural process, which is a part of plant developmental programme. However, the onset of senescence can be greatly influenced by external conditions. An important part of plant senescence is a senescence of leaves manifested by chloroplasts breakdown. That is connected to mobilization of nitrogen contained in proteins, which provide their function. However, the correct timing of natural senescence is substantive for the plant. The initiation as well as the process of natural senescence is influenced by several factors. Senescence is in varying degrees controlled by phytohormones, regulation factors and it is also driven by epigeneticall processes. Leaf senescence can be caused by several exogenous (light conditions, temperature, water and mineral availability, pathogen attack) and internal (carbohydrate levels, hormones, age, developmental stage) conditions. As well as many other developmental stages, senescence is greatly regulated by phytohormones. Ethylene, abscisic acid, salicyl acid and methyljasmonate support leaf aging, on contrary cytokinins delay senescence associated processes. Studying of cytokinin with chlorophyll analysis is an important part of every study of senescence. This work summarizes literature information of regulation of senescence with an accent on the role...
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