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Role cytokininů v regulaci odpovědi na nedostatek síry u Arabidopsis thaliana
Štuříková, Helena
Sulfur deficiency stress induces a number of adaptive responses which must be coordinated. Phytohormone cytokinin has been previously shown to regulate sulfur aquisition and utilizati-on, however, the cytokinin-regulation of sulfur nutrition remains elusive. In this diploma the-sis, it was reported that cytokinin induces a sulfur-deficiency-like gene expression which is accompanied by a decrease in pool of the key sulfur-containing compound glutathione. Further, it was found that the sulfur deficiency responses involve altered cytokinin status to coordinate developmental and/or metabolic adaptations. Arabidopsis plants deficient in cytokinin signaling showed disrupted root elongation in response to sulfur starvation and, unexpectedly, the root elongation in response to sulfur starvation was further stimulated by a low cytokinin concentration. Further, the role of cytokinin in sulfur nutrition was indicated in cytokinin signaling-deficient plants which accumulated more glutathione under normal nu-tritive conditions in comparison to wild-type, and vice versa, the decrease of glutathione pool was exaggerated during sulfur starvation. Altogether, results of this diploma thesis suggest that cytokinins participate in nutritional sulfur homeostasis control.
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Role cytokininů v regulaci odpovědi na nedostatek síry u Arabidopsis thaliana
Štuříková, Helena
Sulfur deficiency stress induces a number of adaptive responses which must be coordinated. Phytohormone cytokinin has been previously shown to regulate sulfur aquisition and utilizati-on, however, the cytokinin-regulation of sulfur nutrition remains elusive. In this diploma the-sis, it was reported that cytokinin induces a sulfur-deficiency-like gene expression which is accompanied by a decrease in pool of the key sulfur-containing compound glutathione. Further, it was found that the sulfur deficiency responses involve altered cytokinin status to coordinate developmental and/or metabolic adaptations. Arabidopsis plants deficient in cytokinin signaling showed disrupted root elongation in response to sulfur starvation and, unexpectedly, the root elongation in response to sulfur starvation was further stimulated by a low cytokinin concentration. Further, the role of cytokinin in sulfur nutrition was indicated in cytokinin signaling-deficient plants which accumulated more glutathione under normal nu-tritive conditions in comparison to wild-type, and vice versa, the decrease of glutathione pool was exaggerated during sulfur starvation. Altogether, results of this diploma thesis suggest that cytokinins participate in nutritional sulfur homeostasis control.
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Analýza vývoje klíčních transgenních rostlin Arabidopsis thaliana nadprodukující cytokinin-glukosid specifické ß-glukosidasy Zm-p60.1
Štuříková, Helena
In this bachelor thesis the localization of the maize beta-glukosidase Zm-p60.1 was studied in transgenic Arabidopsis plants using histochemical staining and confocal microscopy. Zm-p60.1 plays an important role in cytokinin metabolism, where it participates in the reversible activation of zeatin from its inactive storage form - zeatin-O-glucoside. Histochemical staining confirmed the expression of Zm-p60.1 in root tips, leaf tissues and vasculature. Subsequent, confocal microscopy using a fluorescently (GFP)-labeled version of Zm-p60.1 revealed localization in chloroplasts, plastids (in root tips) and in xylem of vasculature. Localization of Zm-p60.1 in chloroplasts and plastids in Arabidopsis correlates with previous studies in maize (Kristoffersen et al., 2000) and tobacco (Kiran et al., 2006), which indicates the stability of Zm-p60.1 targeting. The expression of Zm-p60.1 in the vasculature is an unexpected finding and needs to be clarified in future research.
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