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Intraspecific variability in plant antioxidant systems and its impact on drought tolerance
Jelénková, Iva ; Kočová, Marie (advisor) ; Zelenková, Sylva (referee)
Drought is one of the major factors limiting agricultural production. Reactive oxygen species (eg. superoxide radical, hydroxyl radical, hydrogen peroxide) generated during stress in plant cells activate antioxidant mechanisms, which scavenge those toxic substances. The positive correlation between activity of enzymatic (eg. catalase, superoxide dismutase, glutathione reductase, peroxidases) and nonenzymatic (eg. glutathione, ascorbic acid) antioxidants and stress tolerance was confirmed in various studies. Both interspecific and intraspecific variability was found in activities of antioxidant systems of plants. Higher activity was also observed in F1 generation in relation to positive heterosis, or in plants treated with supportive substances such as abscisic acid, brassinosteroids and nitrogen. The increase in the activity of antioxidants was also proved in relation to the ploidy level or to intensity of drought. It was observed the positive effect of previous drought exposition on tolerance to other abiotic stressors. The complex response of plants to stress factors depends on many other internal and external factors.
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In vitro selection of rapessed for drought, cold stress and pathogen tolerance
Řehořová, Kateřina ; Zelenková, Sylva (advisor) ; Klíma, Miroslav (referee)
Rapeseed (Brassica napus L.) is one of the three main oil-producing crops in the world. Drought, cold and pathogen are the major stresses, which adversely affect rapeseed growth and productivity. Tissue culture based in vitro selection has emerged as a feasible and cost-effective tool for developing stress-tolerant plants. This review desribes the rape in vitro selections to increase resistance to the above stresses. In recent years, the role of proline was discussed in relation to the induction of resistance to stress. Using in vitro selection, however, has not established that presence of proline as indicative of tolerance to frost or drought. In contrast, while we add abscisic acid exogenously, it can induce resistance to frost and drought, and also affect the concentration of other substances, including proline. Through in vitro selection was discovered that brassinosteroids have the important role during drought, but their mechanisms during stress have not been yet clarified. During exposure of plants to frost, overexpression of new discovered genes increase frost resistence by dehydrin proteins. For rape pathogen, Sclerotinia sclerotiorum, was mainly used oxal acid during in vitro selections as a mushroom toxin, which primarily damages the plant. In the selection of lines resistant to Leptosphaeria...
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Drought, stress and resistance
Kettnerová, Karolína ; Zelenková, Sylva (advisor) ; Rothová, Olga (referee)
This bachleor thesis focuses on the influence of water deficit on plants. The causes of the origins of water deficit and its impact on growth and development of plants are described. Attention is paid to the process of stress response and to the adaptation mechanisms which aimed to induce stress tolerance. Separate chapters are devoted to the cuticle and stomata, two important regulators of plant water loss. The thesis also focuses on the phenomenon of osmotic adjustment which relates to the accumulation of compatible solutes. Signalling pathways induced water shortages, change in gene expression, synthesis of special proteins and consequences of secondary oxidative stress are all covered. Key words: drought, water deficit, stress, stress tolerance, stomata, cuticle, osmotic adjustment, compatible solutes, signal transduction
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Does the synthesis of sugar alcohols represent a general mechanism of plant stress response?
Peldřimovská, Jitka ; Lipavská, Helena (advisor) ; Zelenková, Sylva (referee)
Plants cope with adverse environmental conditions with broad variety of defence mechanisms. One of them is the accumulation of compatible solutes, e.g. carbohydrates including sugar alcohols. The compatible solutes are involved in osmotic adjustment, scavenging of reactive oxygen species and they can protect macromolecules and cell membranes by simulation of water envelopes. The sugar alcohols appear in a large range of plants where they serve as primary products of photosynthesis and are involved in long distance transport of C and energy storage. Homologues of the enzymes of polyol metabolism, however, have been recently found also in the plant species that do not use sugar alcohols for fulfilling of above mentioned basic functions of carbohydrate metabolism and where their role remains elusive. It is well known that some plants are able to switch between different carbohydrates in response to different stresses, and some produce polyols only at a certain stage of development. It is therefore question of further studies, whether the polyols cannot be observed in other plants under specific stress conditions and in certain developmental stages as a part of stress response. The aim of this Bachelor thesis is to summarize knowledge of mannitol and sorbitol roles, and especially their involvement in...
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Utilization of biotechnological method in growing of technical hemp
Širl, Marek ; Zelenková, Sylva (advisor) ; Fischer, Lukáš (referee)
Hemp (Cannabis sativa L.) is a multi-use crop, able to provide fibre celulose and hurds for industrial treatment biomass for energy conversion and produces secondary metabolites useful for pharmaceutical application. For its resistence to stress and ability to accumulate high concentration of heavy metals it can be potentialy used for phytoremediation. The aim of current research is the development of new strains, with specialy improved qualities and the enhancement of its applicability. Besides traditional breeding methods, genetic manipulation might be the possible tool. What is currently discussed is finding optimal conditions allowing efective in vitro cultivation as a basic assumption of genetic manipulation. Hemp transformation via Agrobacterium tumefaciens co-cultivation might be the appropriate technic.
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Intraspecific variability in plant antioxidant systems and its impact on drought tolerance
Jelénková, Iva ; Kočová, Marie (advisor) ; Zelenková, Sylva (referee)
Drought is one of the major factors limiting agricultural production. Reactive oxygen species (eg. superoxide radical, hydroxyl radical, hydrogen peroxide) generated during stress in plant cells activate antioxidant mechanisms, which scavenge those toxic substances. The positive correlation between activity of enzymatic (eg. catalase, superoxide dismutase, glutathione reductase, peroxidases) and nonenzymatic (eg. glutathione, ascorbic acid) antioxidants and stress tolerance was confirmed in various studies. Both interspecific and intraspecific variability was found in activities of antioxidant systems of plants. Higher activity was also observed in F1 generation in relation to positive heterosis, or in plants treated with supportive substances such as abscisic acid, brassinosteroids and nitrogen. The increase in the activity of antioxidants was also proved in relation to the ploidy level or to intensity of drought. It was observed the positive effect of previous drought exposition on tolerance to other abiotic stressors. The complex response of plants to stress factors depends on many other internal and external factors.
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Inter- and intraspecific variability in Vicia faba L. and Zea mays L. response to water deficit
Fridrichová, Lenka ; Holá, Dana (advisor) ; Zelenková, Sylva (referee)
This work monitors the response of plants to water deficit and subsequent restoration of water availability with the aim to expand our knowledge about plant behaviour during and after drought stress from the perspective of two plant species with a different type of photosynthesis. A particular attention was paid to the intraspecific differences and their possible changes during stress and post-stress periods. The plant response was monitored as the changes of selected photosynthetic, morphological and developmental characteristics caused by the cessation of watering for six days followed by a six-day period of renewed optimal water supply. The experiments were carried out on plants with different types of photosynthesis - C3 plant Vicia faba L and C4 plant Zea mays L.; for both plant species, three varieties / genotypes were monitored. The response of both plant species to insufficient water supply differed by the extent of changes in relative water content (RWC), chlorophyll fluorescence parameters, the dry mass of individual leaves (developed during the stress period), the ratio between the aboveground dry mass and dry mass of roots. In drought-stressed plants, downward trend in RWC was observed, as well as the increase of the minimum yield of chlorophyll fluorescence in dark-adapted leaves (F ),...
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