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MikroRNA jednobuněčných řas a rostlin a vliv abiotických stresových faktorů =: MicroRNA in plants and unicellular algae under abiotic stress factors /
Koláčková, Martina
Stress signaling pathway regulates proteins which are critical for reprogramming of metabolic synthesis and gene expression to achieve homeostasis and cellular stability under stress conditions. The understanding of stress signaling mechanism and response will increase the ability to improve plant‘s oralgal resistance to stress. The theoretical part summarizes the current knowledge of biosynthetic pathway and miRNA roles and presents selected model organisms (Chlamydomonas, Arabidopsis). As well, it introduces abiotic stress and seeks links between abiotic factors, secondary metabolites and miRNAs. The experimental part deals with selected abiotic factors [lycorine, UV-C radiation, ZnSe quantum dots (QDs), CO2] and their influence on Chlamydomonas reinhardtii and Arabidopsis thaliana. It has been shown that 100 and 250µM ZnSe QDs in the form of foliar feeding caused oxidative stress in the leaves without morphological changes in Arabidopsis thaliana. Additionaly, 250µM concentration inhibited the viability of Agrobacterium tumefaciens, a Gram-negative bacterium infecting plants, by 60 %. Furthermore, the regulatory biochemical, molecular and post-transcriptional pathways of Chlamydomonas reinhardtii response to UV-C radiation and lycorine were identified. Further, three specific miRNAs (Cre06.g281600, Cre06.g30900, Cre16.g662600) have been studied in connection with carbon concentrating mechanism (CCM) in Chlamydomonas reinhardtii. Expression of mentioned miRNAs had a positive correlation with target mRNA and revealed the potential regulatory role of miRNAs during CCM adaprion and possibility to increase the efficiency of photosynthesis. Despite, the role of epigenetics including miRNA interference is still unclear in the unicellular algae.
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Osmotické přizpůsobení rekombinantních linií ječmene jarního s vyšší tolerancí k suchu a jeho hodnocení v polních podmínkách
Baláž, David
The thesis deals with the role of drought and the effects on growth, morphology and yield of barely. The evaluation of the physiological mechanisms at the level of the osmotic adjustment of plants was done at two locations differing in the soil water regime. These mechanisms were studied on a group of 20 recombinant inbred lines (RIL) derived from crosses between spring barley Jersey (spring malting cultivar) and Syrian landrace Tadmor, which was used as a donor of drought tolerance. The progeny derived from reciprocal crosses were evaluated for yield parameters (thousand grain weight, grain yield per plant, the proportion of grains over 2 mm) and qualitative parameters (starch content and nitrogen content). The physiological status of the plants was evaluated using relative water content, osmotic potential (OP) and proline content as an osmotically active substance. The effect of location on all above mentioned parameters was estimated on parental varieties as well as on RIL lines. According to the results several lines were selected which exhibit relatively high stability of yield and qualitative parameters at both locations. The relationship between the yield parameters and values associated with the mechanism of osmotic adjustment (RWC, OP and proline content) was not clearly demonstrated. Decrease of OP and increase of proline content in plants cultivated under dry conditions at location Žabčice mostly corresponded to increased level of plant wilting, therefore it is possible that only passive mechanism for OP was involved. This mechanism did not affect the drought tolerance.
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