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Molecular mechanisms of heat stress memory in plants
Zelená, Julie ; Hála, Michal (advisor) ; Konrádová, Hana (referee)
Global warming is one of the main factors contributing to the decline in crop yield and overall plant biodiversity. Increasing surface temperatures of the Earth result in heightened demands on plant to cope with heat stress. Heat stress causes various damages to plants, primarily denaturation of cellular proteins, loosening of biomembranes, and accumulation of reactive oxygen species (ROS). Plants cells defend against heat stress through lipid remodeling of membranes, increased production of ROS scavengers, and primarily increased production of heat shock proteins (HSP), which are molecular chaperons maintaining proteins properly folded even at temperatures that would otherwise cause denaturation. Plants have developed mechanism to cope with recurring heat stress, such as heat waves, that is referred to as acquired thermotolerance and is enabled by the plant's ability to undergo stress memory. Key to stress memory is priming, which involves preparing the plant for very strong heat stress by exposing it to milder heat stress beforehand. Following priming, there comes a memory period, that is also called recovery period, during which the cell maintains altered molecular expression and physiology. The mechanisms of heat stress memory are divided into transcriptional and post- transcriptional,...
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Chromatin modifications and small regulatory RNA in plant intergenerational and transgenerational stress memory: experiments in plants subjected to drought
Macek, Jan ; Holá, Dana (advisor) ; Čermák, Vojtěch (referee)
Water is important for many vital processes, and a lack of water in plants causes drought stress. In case plants survive drought, they can be better adapted for subsequent drought periods. This is defined as stress memory, which will last for a certain period after the stress ended, and can even be transmitted to offspring to help it deal with stressful environment. In such case it is called an inter- or transgenerational stress memory and is probably mediated by chromatin modifications or non-coding RNAs. In this thesis, I collected and discussed original papers dealing with the molecular basis of this phenomenon in drought-stressed plants, focusing mostly on various methodical aspects. It is evident that the maintenance of chromatin modifications across generations is quite a complex process. Currently available information is still scarce, concerns mostly DNA methylation, is incomplete and conflicting. To better understand this topic in the future, the methods of analysis of these modifications need to be adjusted (and focus also on histone modifications), the general design of the experiments has to be improved (analysed generations subjected to stress/control conditions, drought verification, number of replicates) and some factors that can affect plant stress memory should be purposefully...
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A possible role of proline in plant stress memory
Ušák, David ; Holá, Dana (advisor) ; Konrádová, Hana (referee)
The previous exposure to abiotic stress such as drought may prime plants, leading to their improved response upon later stress onset. This phenomenon, called plant stress memory, is linked to a plethora of mechanisms exerted on several levels. A complex analysis of proline metabolism in leaves and roots was performed to test the putative role of proline in such response to recurrent stress, represented by two periods of water deficit, interrupted by a period of rewatering during recovery. To provide a better understanding of intraspecific differences in drought stress memory response of plants and its inheritance, maize (Zea mays L.) parental genotypes with differing drought sensitivity and their F1 reciprocal hybrid offspring were chosen as the plant material. The water deficit had a more pronounced effect on proline metabolism in leaves than in roots. The proline content increased in response to drought, which was linked to a higher proline biosynthesis and a lower proline catabolism. Marked differences in proline metabolism among genotypes were observed, confirming the previous findings that recurrent drought response is not conserved even within the same species. However, contrary to the original assumptions on the role of proline in plant stress memory, the statistical analysis showed that...
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