Cell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsii

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dc.contributor.advisorFarrant, Jill Men_ZA
dc.contributor.advisorDriouich, Azeddineen_ZA
dc.contributor.authorVicre, Maїtéen_ZA
dc.date.accessioned2014-10-25T18:58:50Z
dc.date.available2014-10-25T18:58:50Z
dc.date.issued2001en_ZA
dc.descriptionBibliography: leaves 92-129.en_ZA
dc.description.abstractResurrection plants have the unique capacity to revive from an air-dried state. In order to cope with desiccation, resurrection plants have to overcome a number of stresses, mechanical stress being one. This occurs when the cytoplasm shrinks creating tension between the plasma membrane and the cell wall. In leaves of the Craterostigma species, an extensive shrinkage occurs during drying as well as a considerable wall folding. It is thought that this folding is a well controlled process rather than a simple collapse and that the ability of the wall to fold is important for the viability of the tissues upon drying. The aim of this study was to characterize the cell wall architecture and composition in hydrated and dry leaves of C. wilmsii using microscopical and biochemical techniques. Calcium and hormone contents were also determined during drying. The development of anhydrous fixation for microscopy confirmed the important folding of the wall previously observed with chemical fixation. Using immunocytochemical techniques and a variety of well characterized antibodies, the nature and composition of wall polymers was investigated. There was nothing unusual in the wall composition of C. wilmsii leaves as compared with other dicotyledonous plants. The results show a significant increase of the hemicellulosic polysaccharide xyloglucan and of the unesterified pectins during drying with levels declining again during rehydration. In contrast no increase was observed in others polysaccharides such as ß (1-4) galactans and methylesterified pectins. Biochemical analysis allowed further characterization of cell wall composition of C. wilmsii. The data demonstrate marked changes in the pectic and hemicellulosic wall fraction from dry plants compared to hydrated ones. The most conspicuous change was a decrease in glucose content in the hemicellulose fraction of the dry plant. Together these findings show that dehydration causes important alteration of polysaccharides content in the cell wall of C. wilmsii. Such modifications might be involved in the modulation of the mechanical properties of the wall during dehydration. Furthermore calcium ions content was shown to increase in the cell wall of dry plants, this could also have a role in stabilizing the wall architecture. All these alterations might be under the control of auxin, an hormone whose content was shown to increase during dehydration.en_ZA
dc.identifier.apacitationVicre, M. (2001). <i>Cell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsii</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/8774en_ZA
dc.identifier.chicagocitationVicre, Maїté. <i>"Cell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsii."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2001. http://hdl.handle.net/11427/8774en_ZA
dc.identifier.citationVicre, M. 2001. Cell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsii. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Vicre, Maїté AB - Resurrection plants have the unique capacity to revive from an air-dried state. In order to cope with desiccation, resurrection plants have to overcome a number of stresses, mechanical stress being one. This occurs when the cytoplasm shrinks creating tension between the plasma membrane and the cell wall. In leaves of the Craterostigma species, an extensive shrinkage occurs during drying as well as a considerable wall folding. It is thought that this folding is a well controlled process rather than a simple collapse and that the ability of the wall to fold is important for the viability of the tissues upon drying. The aim of this study was to characterize the cell wall architecture and composition in hydrated and dry leaves of C. wilmsii using microscopical and biochemical techniques. Calcium and hormone contents were also determined during drying. The development of anhydrous fixation for microscopy confirmed the important folding of the wall previously observed with chemical fixation. Using immunocytochemical techniques and a variety of well characterized antibodies, the nature and composition of wall polymers was investigated. There was nothing unusual in the wall composition of C. wilmsii leaves as compared with other dicotyledonous plants. The results show a significant increase of the hemicellulosic polysaccharide xyloglucan and of the unesterified pectins during drying with levels declining again during rehydration. In contrast no increase was observed in others polysaccharides such as ß (1-4) galactans and methylesterified pectins. Biochemical analysis allowed further characterization of cell wall composition of C. wilmsii. The data demonstrate marked changes in the pectic and hemicellulosic wall fraction from dry plants compared to hydrated ones. The most conspicuous change was a decrease in glucose content in the hemicellulose fraction of the dry plant. Together these findings show that dehydration causes important alteration of polysaccharides content in the cell wall of C. wilmsii. Such modifications might be involved in the modulation of the mechanical properties of the wall during dehydration. Furthermore calcium ions content was shown to increase in the cell wall of dry plants, this could also have a role in stabilizing the wall architecture. All these alterations might be under the control of auxin, an hormone whose content was shown to increase during dehydration. DA - 2001 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2001 T1 - Cell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsii TI - Cell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsii UR - http://hdl.handle.net/11427/8774 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/8774
dc.identifier.vancouvercitationVicre M. Cell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsii. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 2001 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/8774en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherBotanyen_ZA
dc.titleCell wall involvement in desiccation tolerance in the resurrection plant Craterostigma wilmsiien_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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