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Variability in the response of exodermis to nutrient deficiencies in the environment
Klvaňová, Renáta ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
v angličtině Plant growth and development is largely dependent on the soil environment which is a source of minerals and water needed for plants to survive. However, the availability of these resources in the soil is very heterogenous and important elements can be leached into the lower parts of the soil or bound to soil particles. Plants have therefore developed a number of adaptations during evolution to increase the efficiency of the root system. One of these aspects are the apoplastic barriers (endodermis and exodermis). Both of these layers affect the transport of substances to and from the root, thereby limiting unregulated apoplastic transport through modifications of the cell walls where the polymers that limit the transport of substances are deposited. These are Casparian bands and suberin lamellae. They often differentiate more rapidly when plants are faced with a stress factor such as drought, salinity or toxicity. However, nutrient deficiencies (e.g. N, P, K and Fe) also affect the rate of differentation. Deficiencies can result in both acceleration and deceleration of differentation, which seems to help optimize root transport properties according to the current conditions. However, this reaction has been less studied so far. This work therefore focuses on the analysis of the response...
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Variability and mechanisms of exodermis differentiation in plant roots
Blascheová, Zuzana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Environmental conditions affect the formation of apoplastic barriers (endodermis and exodermis) in roots. This was shown on many species in many research papers. The exodermal layer is more variable in response to stress conditions than endodermal layer. Cadmium toxicity, as many other stresses, induces faster development of apoplastic barriers. Most of research papers published so far, however characterized only the response of main root to this type of stress factor. Lateral roots, an important part of the root system absorptive surface, are neglected and there is not much information about their response to cadmium stress. The pattern of apoplastic barriers development was therefore analysed in main and also in lateral roots of various size and position on maternal root axis. We found significant differences in response to cadmium stress among these different root types. Then we summed up the differences between these types of roots. Short lateral roots were generally more responsive to cadmium stress, cadmium affected root branching as well as differentiation of apoplastic barriers in lateral roots. These results help us to better understand the response of complex roots system to environmental conditions. In the second part of this work, the role of CASP genes in exodermal development was...
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Effect of exodermis differentiation on nutrient uptake localization in root
Janoušková, Jana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Plants are able to cope with changing environmental conditions or withstand its adverse effects due to their plastic development. One way to adapt to fluctuating amounts of nutrients and water in the environment or the presence of toxic substances is to regulate the movement of substances between the plant and the environment. Beside other, this regulation is also possible at the level of the root system, by the formation of apoplastic barriers endodermis and exodermis. Some species posses endodermis only, in others exodermis in hypodrermal layers of the root can be found. These barriers differentiate in three stages and prevent free movement of coumpounds though apoplast. The transport to the symplast is the key point of regulating the uptake of substances into the plant and the endodermis is the fundamental structure. The presence of exodermis, however, affects the apoplast permeability of the surface root layers and can therefore influence the involvement of the primary cortex cells in the uptake of substances from the environment. In this work the impact of phosphate deficiency on the formation of apoplastic barriers was studied focusing on exodermis and the effect of its differentiation on the occurrence of membrane transporters and involvement of primary cortex cells in the uptake of...
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Mechanisms of exodermal response to nutrient availability in the environment
Gargoš, Ondřej ; Tylová, Edita (advisor) ; Kummerová, Marie (referee)
in English The apoplastic barriers of the root (endodermis and exodermis) represent an important regulatory mechanism for the uptake of water and nutrients from the environment, ensuring its selectivity. In addition, both layers respond to stress factors by altering its rate and degree of cell wall modification, which affects the transport properties of the root and represents adaptive plants to high heterogeneity of the soil environment. Apoplastic barriers also respond to the availability of mineral nutrients. This issue has recently been intensively studied and a number of ambiguities persist. Interestingly, the deficiency of some mineral nutrients stimulates the differentiation of barriers, while the deficiency of other mineral nutrients delays the differentiation. In addition, different plant species react differently to the deficiency of the same element. Another interesting aspect is the fact that the reaction of the endodermis and exodermis is localized and takes place mainly in that part of the root system which is directly exposed to the stress factor. This phenomenon has been observed with cadmium toxicity, but more recently with local nutrient deficiencies (nitrogen and potassium) in Zea mays. This diploma thesis deals with the functional significance of localized enhancing or delaying...
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Effect of exodermis differentiation on nutrient uptake localization in root
Janoušková, Jana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Plants are able to cope with changing environmental conditions or withstand its adverse effects due to their plastic development. One way to adapt to fluctuating amounts of nutrients and water in the environment or the presence of toxic substances is to regulate the movement of substances between the plant and the environment. Beside other, this regulation is also possible at the level of the root system, by the formation of apoplastic barriers endodermis and exodermis. Some species posses endodermis only, in others exodermis in hypodrermal layers of the root can be found. These barriers differentiate in three stages and prevent free movement of coumpounds though apoplast. The transport to the symplast is the key point of regulating the uptake of substances into the plant and the endodermis is the fundamental structure. The presence of exodermis, however, affects the apoplast permeability of the surface root layers and can therefore influence the involvement of the primary cortex cells in the uptake of substances from the environment. In this work the impact of phosphate deficiency on the formation of apoplastic barriers was studied focusing on exodermis and the effect of its differentiation on the occurrence of membrane transporters and involvement of primary cortex cells in the uptake of...
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Exodermis differentiation under nutrient deficiency, effects of phytohormones.
Namyslov, Jiří ; Tylová, Edita (advisor) ; Martinka, Michal (referee)
Apoplastic barriers (exodermis and endodermis) control free movement of substances by apoplast, which is achieved by specific cell wall modifications. Differentiation of these barriers is to some extent variable. It has been demonstrated many times that the differentiation of root apoplastic barriers is strongly influenced by unfavourable environmental conditions. Many stress factors accelerate the deposition of apoplastic barriers. This work deals with the relationship between availability of nutrients and development of root barriers and mechanisms of coordination of developmental processes in roots, including the involvement of auxin and other phytohormones in the coordination of these processes. The exodermis developmental plasticity is followed in maize (Zea mays L.) under conditions of various nutrient deficiencies. The most important results are presented by anatomical analysis, which shows a significant acceleration of exodermis and endodermis differentiation in the N and P deficiency on the contrary, the slowing of differentiation in the absence of Fe and K. This effect is apparently a result of systemic rather than local root system responses because it was not observed with localized deficiency. This thesis also test the influence of some phytohormones on the development of apoplastic...
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Variability and mechanisms of exodermis differentiation in plant roots
Blascheová, Zuzana ; Tylová, Edita (advisor) ; Konrádová, Hana (referee)
Environmental conditions affect the formation of apoplastic barriers (endodermis and exodermis) in roots. This was shown on many species in many research papers. The exodermal layer is more variable in response to stress conditions than endodermal layer. Cadmium toxicity, as many other stresses, induces faster development of apoplastic barriers. Most of research papers published so far, however characterized only the response of main root to this type of stress factor. Lateral roots, an important part of the root system absorptive surface, are neglected and there is not much information about their response to cadmium stress. The pattern of apoplastic barriers development was therefore analysed in main and also in lateral roots of various size and position on maternal root axis. We found significant differences in response to cadmium stress among these different root types. Then we summed up the differences between these types of roots. Short lateral roots were generally more responsive to cadmium stress, cadmium affected root branching as well as differentiation of apoplastic barriers in lateral roots. These results help us to better understand the response of complex roots system to environmental conditions. In the second part of this work, the role of CASP genes in exodermal development was...
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Phylogenic and developmental plasticity of structure of endo and exodermis in roots of higher plants
Szutkowská, Veronika ; Soukup, Aleš (advisor) ; Srba, Miroslav (referee)
Root endodermis and exodermis form apoplastic barriers for the movement of water and solutes into and out of the plant root system. Both layers have modified cell walls with Casparian strips. They often develope suberin lamela as a secondary development stage and thickened cellulose, sometimes lignified, wall as a tertiary development stage. Endodermis, as the innermost layer of cortex, is generally present in all vascular plant roots except Lycopodium. It is very phylogenetically and developmentally stable and in most cases single-layered. Exodermis can be often multi-layered or dimorphic and is formed on the periphery of the root. This layer can be found in a large number of angiosperms but according to the data gathered so far it seems that most of the seedless plants and gymnosperms lack it. Its presence correlates with the environmental conditions in which plants grow and its high structural and developmental plasticity helps roots to resist stress conditions such as drought, salinity, anoxic conditions and the presence of toxic substances. This paper aims to summarize the current knowledge of interspecies variability and developmental plasticity of endodermis and exodermis in roots of vascular plants.
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