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Phytohormones produced by Leptosphaeria maculans as effectors manipulating plant signaling pathways
Krutinová, Hana ; Ryšlavá, Helena (advisor) ; Moserová, Michaela (referee)
Leptosphaeria maculans is the causal agent of blackleg disease in Brassica napus. In this thesis the ability of L. maculans to produce certain phytohormones was established. The thesis focused on auxins and brassinosteroids. Most commonly occurring natural auxin, IAA, and its inactive oxidation product, OxIAA, were found in highest concentration. In plants infected with L. maculans the concentration of OxIAA was higher when compared to control water- treated plants. A surprising difference in IAA production between two sister isolates of L. maculans was discovered. In chemically defined cultivation medium Gamborg JN2 isolate did not produce any IAA. JN3 on the other hand produced IAA in concentration around 1000 pmol/g FW. This difference was used for studying L. maculans putative auxin synthesizing genes. The candidate genes were identified as orthologs of Arabidopsis thaliana genes (YUCCA1.1, NIT1.2) and Ustilago maydis (IAD1.2, TAM1-2.1). An increased transcription level of the auxin biosynthesis candidate genes was observed in JN2 treated in vitro with auxin precursors (tryptophan, tryptamine). Increased IAA concentration was observed as well. No such effect was observed in JN3. Surprisingly, an increased candidate gene transcription and IAA concentration was observed also in JN2 treated with...
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Phospholipase D Beta in hormonal signaling of Arabidopsis Thaliana
Krutinová, Hana ; Ryšlavá, Helena (advisor) ; Hýsková, Veronika (referee)
Plants, as well as all other living organisms, have to react to environmental changes and are forced to put up with the danger that comes from their environment. As a response to this danger, a sophisticated defense system, which moderates responses to stress cues, comes from the outside as well as created inside the plant itself, has evolved in plants. The signaling in this system is mediated by a number of phytohormones, which include salicylic acid, jasmonic acid, abscisic acid, ethylen and auxins. The phytohormone signaling results in a transcription of specific genes. One of the essential components of this signaling network is the phospholipid signaling system, where enzymes called phospholipases play a major role. These enzymes catalyze the hydrolysis of phospholipids, which are part of cellular membranes and products of the hydrolysis can act as signal transferring molecules. In this thesis we studied the potential engagement of phospholipase Dβ isoform into signaling pathways, using an Arabidopsis thaliana mutant plant with mutations in both genes coding phospholipase Dβ. Firstly, we verified that wild type phospholipase Dβ mRNA is not being transcribed in the mutant plants. Subsequently, we compared mutant and wild type plants' reactions to mechanical wounding, pathogen infection and...
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Phytohormones produced by Leptosphaeria maculans as effectors manipulating plant signaling pathways
Krutinová, Hana ; Ryšlavá, Helena (advisor) ; Moserová, Michaela (referee)
Leptosphaeria maculans is the causal agent of blackleg disease in Brassica napus. In this thesis the ability of L. maculans to produce certain phytohormones was established. The thesis focused on auxins and brassinosteroids. Most commonly occurring natural auxin, IAA, and its inactive oxidation product, OxIAA, were found in highest concentration. In plants infected with L. maculans the concentration of OxIAA was higher when compared to control water- treated plants. A surprising difference in IAA production between two sister isolates of L. maculans was discovered. In chemically defined cultivation medium Gamborg JN2 isolate did not produce any IAA. JN3 on the other hand produced IAA in concentration around 1000 pmol/g FW. This difference was used for studying L. maculans putative auxin synthesizing genes. The candidate genes were identified as orthologs of Arabidopsis thaliana genes (YUCCA1.1, NIT1.2) and Ustilago maydis (IAD1.2, TAM1-2.1). An increased transcription level of the auxin biosynthesis candidate genes was observed in JN2 treated in vitro with auxin precursors (tryptophan, tryptamine). Increased IAA concentration was observed as well. No such effect was observed in JN3. Surprisingly, an increased candidate gene transcription and IAA concentration was observed also in JN2 treated with...
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Phospholipase D Beta in hormonal signaling of Arabidopsis Thaliana
Krutinová, Hana ; Ryšlavá, Helena (advisor) ; Hýsková, Veronika (referee)
Plants, as well as all other living organisms, have to react to environmental changes and are forced to put up with the danger that comes from their environment. As a response to this danger, a sophisticated defense system, which moderates responses to stress cues, comes from the outside as well as created inside the plant itself, has evolved in plants. The signaling in this system is mediated by a number of phytohormones, which include salicylic acid, jasmonic acid, abscisic acid, ethylen and auxins. The phytohormone signaling results in a transcription of specific genes. One of the essential components of this signaling network is the phospholipid signaling system, where enzymes called phospholipases play a major role. These enzymes catalyze the hydrolysis of phospholipids, which are part of cellular membranes and products of the hydrolysis can act as signal transferring molecules. In this thesis we studied the potential engagement of phospholipase Dβ isoform into signaling pathways, using an Arabidopsis thaliana mutant plant with mutations in both genes coding phospholipase Dβ. Firstly, we verified that wild type phospholipase Dβ mRNA is not being transcribed in the mutant plants. Subsequently, we compared mutant and wild type plants' reactions to mechanical wounding, pathogen infection and...
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