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Intraspecific variability in plant antioxidant systems and its impact on drought tolerance
Jelénková, Iva ; Kočová, Marie (advisor) ; Zelenková, Sylva (referee)
Drought is one of the major factors limiting agricultural production. Reactive oxygen species (eg. superoxide radical, hydroxyl radical, hydrogen peroxide) generated during stress in plant cells activate antioxidant mechanisms, which scavenge those toxic substances. The positive correlation between activity of enzymatic (eg. catalase, superoxide dismutase, glutathione reductase, peroxidases) and nonenzymatic (eg. glutathione, ascorbic acid) antioxidants and stress tolerance was confirmed in various studies. Both interspecific and intraspecific variability was found in activities of antioxidant systems of plants. Higher activity was also observed in F1 generation in relation to positive heterosis, or in plants treated with supportive substances such as abscisic acid, brassinosteroids and nitrogen. The increase in the activity of antioxidants was also proved in relation to the ploidy level or to intensity of drought. It was observed the positive effect of previous drought exposition on tolerance to other abiotic stressors. The complex response of plants to stress factors depends on many other internal and external factors.
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Polyploidy in sturgeons
SRP, Jiří
The aim was to study the theoretical backgrounds of sturgeon fish genetics, focusing on aspects of polyploidy cytogenetics and to learn basics of reproduction and rearing of sturgeon fish in conditions of Central European aquaculture. The work describes an overview of methods for determining ploidy levels in fish, methods of artificial reproduction, methods of fish marking, sampling and evaluation of population samples for cytogenetic analysis. The experimental part dealt with samples of different sturgeon species and their hybrids, and the effects of spontaneous polyploidy and interspecific hybridization on biodiversity conservation of these endangered species were discussed.
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