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Tissue-specific knockout of starch synthesis in columella cells of Arabidopsis thaliana and gravitropic response
Bogdan, Michal ; Fendrych, Matyáš (advisor) ; Retzer, Katarzyna (referee)
Since the studies of plant gravitropism by Charles Darwin, the identity of specific sensors of gravity in plants has been uncertain. To this date, statoliths - starch granules in the root tips - are considered to play a key role in gravity sensing. The role of statoliths as organelles that mediate the gravity sensing ability of plant roots is based on research that uses plants which have severely impaired ability to synthesize starch in general or have their cells that contain statoliths removed or damaged. This represents methodical imperfections that give rise to alternative explanations, like disturbed auxin flow due to heavy damage to the root tip or unknown involvement of starch from other parts of the plant in gravity perception. Thanks to advances in the field of CRISPR/Cas9 technology, we are now able to produce tissue-specific mutants that might help with clarification of whether starch granules in the root tip are involved in sensing gravity and if so, how significant is this involvement. This diploma thesis aimed to answer these questions by adapting the tissue-specific CRISPR/Cas9 system and using it for the creation of mutants that are starchless specifically in the columella cells. Using this approach, we generated one tissue non-specific mutant line and three tissue-specific mutant...
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Molecular basis for regulation of cell wall pH in Arabidopsis thaliana
Bogdan, Michal ; Fendrych, Matyáš (advisor) ; Retzer, Katarzyna (referee)
The cell wall is one of the defining parts of the plant cell. Cell walls resist turgor pressure, give plants their rigidity and still allow the cell to grow despite their stiffness. The plant cell wall is a composite material that consists of different elements; thus, the knowledge of the plant cell wall composition helps us understand the impact of the mentioned pH changes. Alterations of plant cell wall properties result in a change of plant cell growth rate. A prime example of this is the modification of wall properties by pH change, termed the acid growth. Although acid growth has been studied for a long time, we still do not fully understand the underlying mechanisms, as we have not yet identified all the agents involved in acid growth and our ability to determine apoplastic pH is limited. Local cell wall pH fluctuations arise also due to plant organs having different roles and being affected by a diverse range of stimuli. Despite the fact that new pH measurement techniques, such as genetically encoded fluorescent probes, were developed in the last two decades, there is still a need to provide a higher spatiotemporal resolution of pH analysis. Key words: Arabidopsis, apoplastic pH, cell growth, acid growth theory, cell wall, auxin, apoplastic pH measurement
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