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Mechanisms of epidermal cells polarization in plants.
Vojtíková, Zdeňka ; Žárský, Viktor (advisor) ; Soukup, Aleš (referee)
Plant epidermal cells form contact area of the plant, they protect it from impacts of surrounding environment and they mediate the communication with its neighbourhood. In the epidermis there are evenly distributed several cell types with quite specialized morphology (pavement cells, trichomes and guard cells) due to the polarization mechanisms. The cytoskeleton and signal molecules of ROP GTPase family promote the polarized growth. Thanks to polarized growth the cells reach their shapes. The cytoskeleton responds to the signal by expanding the cell, helps with targeting of the secretion to the sites of active growth and mediates polarized formation of the cell wall. On the upper side of the epidermis the cuticle and layer of epicuticular waxex is secreted. The secretion of cuticular components is baso-apicaly polarized. This work summarizes the mechanisms of the polarization in plant epidermal cells discoverd untill now.
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Subunits of exocyst complex in the development of Arabidopsis epidermis
Vojtíková, Zdeňka ; Žárský, Viktor (advisor) ; Soukup, Aleš (referee)
Exocyst is protein complex evolutionary conserved in yeasts, animals and plants, which plays a role in control of cell morphogenesis and polarity. It is a tethering complex whose function is to attach secretory vesicles to specifi c foci on plasma membrane. Complex exocyst is formed by eight subunits. Subunit EXO70 is encoded by 23 paralogue genes in genome of Arabidopsis thaliana. Mutation in paralogue subunit EX070H4 causes defect in trichome maturation. Mutant trichomes have thin, not reinforced cell wall, making them soft and elastic. Transcription of EXO70H4 gene is induced by UV radiation, therefore observations of plants cultivated on UV-B radiation were done. Analysis of mutants cultivated on UV-B radiation revealed hyperaccumulation of vesicules in cytoplasm, which were visible by light microscope. Hyperaccumulation was not observed in control plants cultivated on UV-B radiation, but thickening of cell wall was induced. Th is reaction to UV in trichomes hasn't been described yet. Analysis of cellular localization made with YFP tagged constructs revealed that EXO70H4 localizes into mobile corpuscules associating with Golgi apparatus. It was found with yeast two hybrid system that EXO70H4 interacts with TRS120, subunit of tethering complex TRAPPII which is active in Golgi apparatus....
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Mechanisms of epidermal cells polarization in plants.
Vojtíková, Zdeňka ; Žárský, Viktor (advisor) ; Soukup, Aleš (referee)
Plant epidermal cells form contact area of the plant, they protect it from impacts of surrounding environment and they mediate the communication with its neighbourhood. In the epidermis there are evenly distributed several cell types with quite specialized morphology (pavement cells, trichomes and guard cells) due to the polarization mechanisms. The cytoskeleton and signal molecules of ROP GTPase family promote the polarized growth. Thanks to polarized growth the cells reach their shapes. The cytoskeleton responds to the signal by expanding the cell, helps with targeting of the secretion to the sites of active growth and mediates polarized formation of the cell wall. On the upper side of the epidermis the cuticle and layer of epicuticular waxex is secreted. The secretion of cuticular components is baso-apicaly polarized. This work summarizes the mechanisms of the polarization in plant epidermal cells discoverd untill now.
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