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Effect of Schizosaccharomyces pombe cdc25 Expression on Morphogenesis in Tobacco Nicotiana tabacum L., cv.Samsun
Uchytilová, Lucie ; Lipavská, Helena (advisor) ; Macháčková, Ivana (referee)
Morphogenetic processes including process of de novo organ formation is governed by the rate, frequency and orientation of cell division. Cell cycle is a complex process with complicated regulation. CDKs (cyclin-dependent kinases) are taken for the key proteins regulating cell cycle progression. These proteins are well conserved among eucaryotic organisms. CDK activity strictly depends on specific subunit - cyclin. The activity of the CDK-cyclin complex can be further modified besides others by phosphorylation/dephosphorylation. In yeast (and in most eukaryotic organisms) activating defosforalation of CDKs is performed by Cdc25 phosphatase. Situation in plants is still not fully elucidated. A small CDC25-like tyrosine-phosphatase was recently identified in Arabidopsis thaliana (Arath;CDC25), which could not, however, complement the temperature sensitive Spcdc25-22 mutant (Landrieu et al., 2004). This study is focused on the effect of expression of the foreign gene (S. pombe) coding for Cdc25 phosphatase on the morphogenesis, especially on the ability of de novo organ formation, in tobacco. Plant material used for experiments: Nicotiana tabacum L., cv. Samsun, wild type, two independent lines transformed with Spcdc25 under a constitutive promotor (designated as lines A and C) (Bell et al., 1993) and...
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The Plant Experimental Models in Centuries - till 1918
Bršťáková, Hana ; Krtková, Jana (advisor) ; Lipavská, Helena (referee)
By 1918, many studies in plant organisms were performed. These laid fundamental building blocks for today's advanced research. To perform the experiments, many plant species were used. My thesis describes, first, which plant species were used in the experiments and second, what kind of discovery was made using them. I focus on plant processes and research fields that were of interest for the scientists then and this strucrure is also followed in my thesis. Each chapter describing individual process or research field is then written in chronological order. Specifically, the discovery of plant cell, selected plant movements such as nutation, phototropism, gravitropism, hydrotropism, plant nutrition and also the first scientific observation of Arabidopsis thaliana are discussed. The goal of this thesis is to introduce the history of selected discoveries in plants and to explain in which plant species the appropriate findings were achieved.
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The role of small RNAs in transgenerational plant stress memory
Jaklová, Veronika ; Marková, Hana (advisor) ; Lipavská, Helena (referee)
Plants are constantly affected by various abiotic and biotic stresses, which cause a whole range of reactions.The resultcanbe increasedplantresistance tovariousstressfactorssuchasherbivoryattack or lack of water. Additionally, this resistance can also be passed on to subsequent generations through epigeneticmechanisms.Small RNAsservingas signaling moleculesof the plant's rapid response tostress can play a large part in the formationof intergenerationalandmultigenerationalstressmemory.MiRNAs are mainly regulators of gene expression,throughtheirinhibitory and degradative activitiesthey control the transcription of genes and the translation of a large number of proteins. SiRNAs could participate in the transfer of transcriptional memory through the mechanism of RNA-directed DNA methylation (RdDM). DNA methylation and histone modifications together act as chromatin marks that can be epigeneticallytransferredtosubsequentgenerations.Basedonthis,plants derivedfromstressedparent plants show large changes in gene expression compared to plants with non-stressed parents. These changesthenpersistfor varyinglengthsof time,dependingon whethergene expressionisagain induced bythe stressfactoror not.Interestinunderstandingthe mechanismsof transgenerationalstressmemory has recently grown considerably, and this...
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Studying the regulation of expression of genes involved in barley malting quality
Hoffmannová, Viktorie ; Svobodová, Leona (advisor) ; Lipavská, Helena (referee)
Barley (Hordeum vulgare L.) is a grain cultivated as an agricultural crop across many varying climatic areas of the world. It is mainly used for its feed and brewing industry properties. This work will focus on studying the malting process on a molecular level, which mainly includes the genes for degradative enzymes of storage proteins, starch and compounds of endosperm cell walls. We shall observe how all these components interact during malting and other processes of brewing beer. It is known that malting quality parameters are tied to several genes, whose expression is regulated. These regulatory pathways will also be included in this work.
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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 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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Potential of genetic engineering for breeding plants tolerant to abiotic stresses: cold resistance in rice
Lotová, Gabriela ; Lipavská, Helena (advisor) ; Janská, Anna (referee)
With increasing population and climate change, there has been an increase in efforts to breed more efficient crops. Genetic engineering has opened unprecedented breeding possibilities in developing plants with desired traits. Transgenic crops with better qualities, including resistance to adverse environmental conditions, can contribute to solving problems of hunger and malnutrition in developing countries. Although society perceives genetically modified crops rather negatively, these crops are widely used as feed for livestock and outside Europe also for human nutrition. Because of the complexity of resistance to abiotic stress, the utility of genetic manipulations for the breeding of resistant plants was previously not anticipated. However, it turned out that modification of the stress signalling cascade or transcription factors can lead to success. This thesis summarizes the possibilities of genetic modification of crops, which may result in better tolerance to cold, and is mainly focused on rice. Part of the work deals with transduction of cold signal, whose modification can also result in increased tolerance to cold. Another part deals with transcription factors that activate expression of low temperature- resistant genes. The greatest attention is paid to CBF/DREB transcription factors that...
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