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Role of the exocyst complex in stomata dynamics
Drs, Matěj ; Pečenková, Tamara (advisor) ; Fendrych, Matyáš (referee)
The exchange of gases between the plant and the environment is mediated by guard cells, which, by changing their volume, regulate the size of the stomatal pore where the exchange takes place. Unique properties of stomata are given by a specifically designed cell wall, allowing asymmetric cell expansion. During the opening of stomata, there is a large increase in turgor pressure, accompanied by the uptake of considerable amount of water. For this reason, it is necessary to quickly change the inner surface of the guard cell. This process is ensured by the dynamic movement of the membranes inside the cell. During these processes, the vesicles are removed from the plasma membrane and reintegrated back during stomatal closure. One of the important regulators of the polarized transport of vesicles within the cell is a multiprotein complex exocyst. Due to the multiplication of exocyst subunits, the exocyst complex functions in plants are extensively diversified and involved in many cellular processes. In this thesis the effect of mutation in subunits exo70B1, exo70B2 and its combination exo70B1/exo70B2, on stomatal dynamics is studied. Both of these mutations affect the opening of the stomata during increased light intensity. The mutation of exo70B1 is in this case affected in greater manner. These...
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Autophagy in plants defence against pathogenes
Drs, Matěj ; Žárský, Viktor (advisor) ; Ponert, Jan (referee)
Autophagy is a degradation process allowing the cell to get rid of unwanted parts of cytopasm by isolating into double layer plasma membrane and subsequent transport into vacuoles. In stressful situations especially at starvation the autophagy activity is highest. And such situation can also be infecting by pathogen. The plant immune system has a number of processes which prevents infection. One of the main defensive mechanisms is programmed cell death (PCD). In plant cell, the PCD may be running by different signal pathways. Immune system includes a specific type of PCD known as hypersensitive reaction (HR), which is an effective defense against pathogens. HR is associated with salicylic acid-dependent signaling (SA) and this pathway is positively and negatively modulated by the process of autophagy. However, the autophagy is involved in other signaling pathways. Necrotrophic pathogens often use fytotoxins to actively kill the host cell. Autophagy probably also participates in the degradation of these fytotoxins. It also plays an important role during signaling dependent on the jasmonic acid (JA) and ethylen (ET). These signaling pathways usually trigger the reactions against necrotrophic pathogens and suppress signal dependet on SA. Autophagy in this case may be preventing the initiation of PCD....
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