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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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Sorbitol role in abiotic stress response
Dvořáková, Iveta ; Konrádová, Hana (advisor) ; Janská, Anna (referee)
Many adverse factors affect plants during their life cycle. This bachelor thesis is focused on the influence of abiotic stress on plants. Attention is paid to drought and salinity stresses which are the main causes of osmotic stress, and to the mechanisms which help plants to cope with these adverse factors. Common reaction of plants to osmotic stress is synthesis and accumulation of substances which contribute to keeping cell integrity. These substances are called compatible solutes. This thesis is focused on sorbitol - sugar alcohol belonging to this group of substances. In plants that synthesize sorbitol naturally, it provides advantage under exposure to abiotic stresses as it serves as an osmoticum and/or an osmoprotectant and reduces oxidative stresses. Finally, based on the knowledge about participation of sugar alcohols in the stress reactions, modifications of plant metabolisms potentially increasing stress tolerance are discussed. Powered by TCPDF (www.tcpdf.org)
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Does the synthesis of sugar alcohols represent a general mechanism of plant stress response?
Peldřimovská, Jitka ; Lipavská, Helena (advisor) ; Zelenková, Sylva (referee)
Plants cope with adverse environmental conditions with broad variety of defence mechanisms. One of them is the accumulation of compatible solutes, e.g. carbohydrates including sugar alcohols. The compatible solutes are involved in osmotic adjustment, scavenging of reactive oxygen species and they can protect macromolecules and cell membranes by simulation of water envelopes. The sugar alcohols appear in a large range of plants where they serve as primary products of photosynthesis and are involved in long distance transport of C and energy storage. Homologues of the enzymes of polyol metabolism, however, have been recently found also in the plant species that do not use sugar alcohols for fulfilling of above mentioned basic functions of carbohydrate metabolism and where their role remains elusive. It is well known that some plants are able to switch between different carbohydrates in response to different stresses, and some produce polyols only at a certain stage of development. It is therefore question of further studies, whether the polyols cannot be observed in other plants under specific stress conditions and in certain developmental stages as a part of stress response. The aim of this Bachelor thesis is to summarize knowledge of mannitol and sorbitol roles, and especially their involvement in...
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