|
|
Function of root apical meristem
Benešová, Šárka ; Soukup, Aleš (advisor) ; Kulich, Ivan (referee)
A root apical meristem is the only source of cells for all tissues in the root. The root growth relies on its function. Regulation of a cell division frequency and cell differentiation affects organization and function of the differentiated tissues and the proper meristem function. If the cell differentiation overbalances the cell proliferation, the meristem exhaustion occurs and the root growth irreversibly terminates. This thesis describes existing knowledge about regulation of the primary root apical meristem of model plants Arabidopsis thaliana and Zea mays, explains these findings in the context of plant postembryonal development and provides informations about how and under what conditions the primary root growth might be terminated.
|
|
|
Phylogenic and developmental plasticity of structure of endo and exodermis in roots of higher plants
Szutkowská, Veronika ; Soukup, Aleš (advisor) ; Srba, Miroslav (referee)
Root endodermis and exodermis form apoplastic barriers for the movement of water and solutes into and out of the plant root system. Both layers have modified cell walls with Casparian strips. They often develope suberin lamela as a secondary development stage and thickened cellulose, sometimes lignified, wall as a tertiary development stage. Endodermis, as the innermost layer of cortex, is generally present in all vascular plant roots except Lycopodium. It is very phylogenetically and developmentally stable and in most cases single-layered. Exodermis can be often multi-layered or dimorphic and is formed on the periphery of the root. This layer can be found in a large number of angiosperms but according to the data gathered so far it seems that most of the seedless plants and gymnosperms lack it. Its presence correlates with the environmental conditions in which plants grow and its high structural and developmental plasticity helps roots to resist stress conditions such as drought, salinity, anoxic conditions and the presence of toxic substances. This paper aims to summarize the current knowledge of interspecies variability and developmental plasticity of endodermis and exodermis in roots of vascular plants.
|
|
|
Lateral root and their origin
Nováková, Hana ; Soukup, Aleš (advisor) ; Sekereš, Juraj (referee)
The origin of lateral roots is one of the determinants of the structure of the overall architecture of the root system of plants. Individual plant species differs in point of initiation of lateral roots in the longitudinal and transverse plane of the parent root. This paper briefly summarizes the findings relating to the establishment and development of lateral roots in the model of plant Arabidopsis thaliana and on the sample of several species of ferns and monocots and dicots of literature outlines the variability that manifests itself especially during initiation of lateral roots. The ferns initiation site located in the endodermis of the parent root, for other species to form the lateral root primordium of pericycle cells that are found in a certain position in relation to vascular elements in the central cylinder of the parent root. Another highly variable factor in the development of lateral root initiation site is the distance from the root apical meristem, which is related to the place of the auxin signal competent cells and also the rate of growth and progress of cells from the parent root apical meristem. Powered by TCPDF (www.tcpdf.org)
|
|
|
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....
|
|
|
Funkce genů rodiny TTL a jejich efekt na tvorbu postranních kořenů u Arabidopsis
Hilgert Delgado, Alois Antonín ; Soukup, Aleš (advisor) ; Cvrčková, Fatima (referee)
The work is focused on the lateral roots, which are an indispensable part of the root system and play a key role in communication with rhizosphere and the efficient exploitation of natural resources. Tetratricopeptide-repeat Thioredoxin-like 3 gene (TTL3) was identified by forward screening based on its gene expression pattern in the search for genes associated with the development of lateral roots in Arabidopsis thaliana. TTL3 also known as VIT (VH1 interacting TPR containing protein), belongs to a family of four paralogues in Arabidopsis showing a very similar arrangement of domains. It seems that this type of proteins is widespread in plants and provides protein-protein signaling as an important component of phytohormone response pathways. The presented diploma thesis is focused on characterization and comparison of expression patterns of the four members of TTL family, through creation of pTTL::uidA (GUS) transcriptional fusions. The promoter area was estimated to be contained in about 2000bp upwards the TTLs coding sequences and transcriptional fusions with uidA gene were individually constructed and transformed into Arabidopsis via Agrobacterium tumefaciens. The expression patterns of analyzed genes were microscopically confirmed and allowed comparison among members of TTL gene family with regard...
|
|
|
Lateral roots and root nodules - similarities and differences
Šnajdrová, Tereza ; Soukup, Aleš (advisor) ; Kulich, Ivan (referee)
Postranní orgány kořene, kořenové hlízky a postranní kořeny, se zakládají endogenně, a až na výjimky mimo apikální meristém. Tyto orgány mohou být různě modifikovány. Některé rostliny mají, právě díky těmto postranním orgánům, schopnost vstupovat do symbiotických interakcí s jinými organismy. Při vzniku symbiotické, dusík-fixující hlízky se uplatňuje signalizace obou budoucích partnerů, aby byl zajištěn vstup do kořene pouze organismu hostitelsky specifickému k rostlině. Pronikání bakterie Rhizobium či Frankia do kořene se standardně děje přes kořenový vlásek pokožkové buňky, ale není to jediný možný mechanismus vstupu. Zároveň s tímto vstupem se začne vytvářet hlízkové primordium. Pletivo, z něhož se hlízka vytváří, i výsledná podoba hlízky, se liší u různých rostlin. V centrální zóně dospělé hlízky dochází, díky nitrát reduktáze, k fixaci vzdušného dusíku. Tato vlastnost zvýhodňuje rostliny, schopné této hlízkové symbiózy, při kolonizaci půdy, chudé na dusík. Postranní kořeny se zakládají v pericyklu, aktivací malého počtu jeho buněk. Po výstupu z pletiv mateřského kořene dochází k aktivaci meristému bočního kořene. Oba tyto postranní orgány spolu s primárním kořenem tvoří dynamický kořenový systém, regulovaný vnitřními i vnějšími faktory.
|
|
|
Comparative anatomy of genus Lasiocephalus - from tropical mountain forest to páramo
Ježková, Barbora ; Soukup, Aleš (advisor) ; Lhotáková, Zuzana (referee)
South American genus Lasiocephalus colonized high altitudes of the tropical Andes, the so called páramo, from lower elevations of the Andean forest. Páramo is a specific high-altitude environment characterised by pronounced diurnal changes in temperature, growing season over the entire year, low average temperatures, generally high humidity, and intense solar radiation. These specific environmental conditions are reflected by anatomical characters of the species. Given the known phylogeny of the group it was possible to observe anatomical adaptations along steep gradient of environmental conditions from forest to páramo. The hypothesis about adaptive changes that occurred during the colonization of the páramo habitats was confirmed. Observed characteristics were, for example, leaf area and thickness, epidermal cells cuticle and cell wall thickness, epidermal cells lumen height, ratio of palisade and spongy parenchyma, stomatal area, stomata length and width, stomata pore length and sieve elements average area. Results suggest that the anatomy of the plants reflect the environmental conditions of the habitats rather than the species phylogeny.
|
|
|
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.
|
|
| |
|
|
Marketing mix of provider of mobile services
Soukup, Aleš ; Vávra, Oldřich (advisor) ; Stříteský, Václav (referee)
Bachelor thesis is focused on Vodafone and their current product called "Tarify na míru" which is analyzed on basis of marketing mix. The aim of this thesis is to specify Czech market of mobile services, position of Vodafone in this market and then introduce their nowadays product and analyse it. Analyses include layers of product concept, product lifecycle, analysis of development of customers, assessment of success of this product and comparison of price based on predetermined price baskets. Data is mined from both resources -- external and internal resources of Vodafone Czech Republic a.s.
|
guest ::
RSS feed.