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AHL genes in plant development
Škrabálková, Eliška ; Širl, Marek (advisor) ; Ortmannová, Jitka (referee)
Plant development is a complex process where different factors come into play. The expression of certain genes, which determine basic plant structure and its signaling pathways, is also of great importance. The AHL gene family, which in case of Arabidopsis thaliana includes 29 members, is one of those determinators that have an impact on plant development on several levels. As far as structure is concerned, the AHL proteins are typically composed of two parts - the DNA-bonding AT-hook motif and PPC domain, which defines nuclear localisation and eventually enables oligomerisation. In terms of phylogenetics, the AHL proteins are divided into clades A and B on the basis of number and type of these domains. When it comes to affecting plant development, these nuclear proteins are capable of bonding with the corresponding DNA, and in cooperation with other factors influencing gene expression. In the plant body the AHL proteins are involved in root and floral organogenesis and also cooperate with a number of signaling pathways of phytohormones, such as auxins, gibberellins, brassinosteroids or senescence hormones. Moreover, they take part in photomorphogenesis or control systematic immune responses of the plant. Keywords: AHL, AT-hook, PPC domain, nuclear protein, Arabidopsis thaliana
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Functional characterisation of AHL28 and its role in root system development
Škrabálková, Eliška ; Širl, Marek (advisor) ; Sabol, Peter (referee)
The root system architecture development is influenced by the interaction of numerous factors, one of which is the specific gene expression contributing to root development. The recently discovered AHL gene family, which, due to its characteristics act as transcriptional modulators, demonstrably comprises members taking part in regulation of root system development. Hereby we report the AHL28 gene that participates in this process. Its regulatory role corresponds with the expression pattern, regarding both the promotor activity and presence of nuclear localised protein. The expression can be observed in the cortex cells of transition zone of both primary and lateral roots. The phenothypic analysis of plants with modulated level of AHL28 transcription demonstrates its role in the primary root growth and differentiation, the apical meristem size and the number of lateral roots. Moreover, the gene also plays a role in vascular tissue patterning. Key words: AHL, nuclear protein, root system, apical meristem, lateral roots, xylem, Arabidopsis thaliana
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Role of sequence context in DNA methylation
Polák, Jan ; Fischer, Lukáš (advisor) ; Širl, Marek (referee)
Cytosine methylation of DNA is a pivotal epigenetic mark, which contributes to the regulation of the gene expresion, silencing of transposable elements, and co-defines chromatine state. There are three cytosine contexts: CG, CHG and CHH (where H stands for C, A, or T). Arabidopsis thaliana (and plants in general) has an arsenal of molecular mechanisms capable of cytosine methylation in all of its contexts. That said, there are two tasks at hand: maintaining of pre-existing methylation and if need be, creating new methylated spots. The actual process of maintaining of the methylation depends on the cytosine context. Methylation of symmetrical contexts of CG and CHG can utilize the information about the methylation pattern from the second DNA strand. The aymmetrical context of CHH, and also CHG need to look for this information elsewhere: in the methylation of the lysine 9 of H3 histone. This creates a self-reinforcing loop and a crosstalk between two epigenetic mechanisms. Maintaince of methylation of CHH is also navigated by small RNA complementary to the locus in question. This mechanism of enzyme navigating by RNA is also used in establishing a new methylated site for all of the contexts. CG methylation is most prevalent in both heterochromatine and euchromatine. It also has a special functions...
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AHL genes in plant development
Škrabálková, Eliška ; Širl, Marek (advisor) ; Ortmannová, Jitka (referee)
Plant development is a complex process where different factors come into play. The expression of certain genes, which determine basic plant structure and its signaling pathways, is also of great importance. The AHL gene family, which in case of Arabidopsis thaliana includes 29 members, is one of those determinators that have an impact on plant development on several levels. As far as structure is concerned, the AHL proteins are typically composed of two parts - the DNA-bonding AT-hook motif and PPC domain, which defines nuclear localisation and eventually enables oligomerisation. In terms of phylogenetics, the AHL proteins are divided into clades A and B on the basis of number and type of these domains. When it comes to affecting plant development, these nuclear proteins are capable of bonding with the corresponding DNA, and in cooperation with other factors influencing gene expression. In the plant body the AHL proteins are involved in root and floral organogenesis and also cooperate with a number of signaling pathways of phytohormones, such as auxins, gibberellins, brassinosteroids or senescence hormones. Moreover, they take part in photomorphogenesis or control systematic immune responses of the plant. Keywords: AHL, AT-hook, PPC domain, nuclear protein, Arabidopsis thaliana
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Study of factors influencing efficiency of Canabis sativa transformation
Širl, Marek ; Ovesná, Jaroslava (advisor) ; Vondráková, Zuzana (referee)
Hemp (Cannabis sativa L.) is a multi-use crop, able to provide fibre celulose a hurds for industrial treatment seeds for oil preparation biomass for energy conversion and produces secondary metabolites useful for pharmaceutical application. For its resistence to stress ability to accumulate high concentration of heavy metals and low cultivations demands, it can also be used for phytoextractions. Current research is focused on establishment of cultivation protocol, which allows transformation of callus cultures, and their regeneration with high efficiency. In this thesis, several varieties of hemp were transferred to in vitro conditions and were tested for their ability to form callus. The best results were achieved using the hypocotyl segments in a nutrient medium supplemented with 1 mg/L of naphtylacetic acid and one of these two synthetic cytokinins 0,5 mg/L of thidiazuron or 5 mg/L of 6-benzylaminopurine. No significant difference in the use of these two cytokinins were observed. None of the explants on four different test media for regeneration of shoots were able to succesfully regenerate. Transformation of hemp was tested using two different methods. Transformed protoplasts from hemp leafs after agroinfiltration were isolated. This method turn out to be unsuitable for use with hemp due to its...
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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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