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The effect of 24-epibrassinolide on selected parameters of maize and faba bean genotypes varying in drought sensitivity
Řehořová, Kateřina ; Kočová, Marie (advisor) ; Hniličková, Helena (referee)
Brassinosteroids are plant hormones which are also known for their pleiotropic effects on plants exposed to various biotic and abiotic stress factors. The aim of this study was to evaluate the role of 10-8 M 24-epibrassinolide in Zea mays L. and Vicia faba L., grown under conditions of drought stress (6, 10, 14, 18 days) with an emphasis on different answer to their drought sensitive and resistant genotypes. Net photosynthetic rate (PN) and transpiration rate (E), stomatal conductance (gs), osmotic potential (ψs), proline (Pro) and malondialdehyde (MDA) content and membrane injury index (MI) were measured in stressed plants and plants grown under controlled conditions. The most important factor influencing these parameters was drought, which led to a gradual decrease of PN, E, gs, ψs and increase of Pro, MDA a MI. The effect of 24-epibrassinolid was significant rather exceptionally and in these cases, more pronounced response was observed in drought stressed plants compared with plants grown under controlled conditions. Plants showed intraspecific variability in their reactions, which in sensitive and tolerant genotypes were not clear and differed depending on the studied parameters and conditions of plant cultivation.
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English language newspapers in the Czech republic between 1990 and 1995 as a part of process of transformation of the press in post-communist country
Řehořová, Kateřina ; Jirák, Jan (advisor) ; Cebe, Jan (referee)
The diploma thesis deals with English language periodicals which were founded and published by Americans in Prague in 1990 - 1995. The first part describes the background of the American community in Prague in the middle 1990s and apprises of the American and Czechoslovak journalism in the frame of media system changes after the fall of Communism. The second part includes newspapers and magazines which existed in Prague the defined period. Except of print media articles, literature concerned with media transformation after the fall of totalitarian regimes and features of American and Czechoslovak journalism the thesis is based on correspondence and interviews with people who are allied to the included periodicals. At the end of the thesis there is a review of the impact that American journalists and writers could have on Czechoslovak and Czech journalism and literature. The influence of American journalists on the Czechoslovak and Czech colleagues remains in form of individual cases. The influence of American literature written in Prague in the defined period has not overreached the English language sphere and so it cannot be considered in the general context of Czechoslovak and Czech literature.
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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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