The functional analysis of XhLEA3-2 - a LEA_4 from the resurrection plant, Xerophyta humilis

 

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dc.contributor.advisor Farrant, Jill M en_ZA
dc.contributor.advisor Rafudeen, Suhail en_ZA
dc.contributor.author Dennis, Timothy James en_ZA
dc.date.accessioned 2018-01-30T10:24:55Z
dc.date.available 2018-01-30T10:24:55Z
dc.date.issued 2017 en_ZA
dc.identifier.citation Dennis, T. 2017. The functional analysis of XhLEA3-2 - a LEA_4 from the resurrection plant, Xerophyta humilis. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/27094
dc.description.abstract Climate change is a pressing reality in the current era. Changing environmental conditions and limited water availability are associated with the loss of arable land in areas where farming has traditionally thrived. Thus, linked to climate change, is the risk of a global food shortage. Resurrection plants are phenomenal in that they are able to survive extended periods of drought in a state of anhydrobiosis and then resume full metabolism upon rehydration. These plants serve as models to scientists and genetic engineers who hope to replicate, to a degree, the 'resurrection phenomenon' in drought sensitive crop species. The ability of resurrection plants to survive drought needs to be studied on a molecular level if it is to be implemented in transgenic crops. Currently, the molecular mechanisms of desiccation tolerance are only somewhat understood, and considerable investigation is still required. Xerophyta humilis is a monocotyledonous resurrection plant in which one of the responses to extreme water loss is the upregulation of several Late Embryogenesis Abundant (LEA) genes. The protein products of these genes, called LEA proteins, are known to be correlated with abiotic stress tolerance in plants, invertebrates and microorganisms. However, the precise molecular mode(s) of action of LEA proteins are still poorly understood. In this study, a group LEA_4, LEA protein, which we have termed XhLEA3-2, shown to be transcriptionally upregulated during desiccation of the resurrection plant X. humilis, has been characterized. A bioinformatic, predictive analysis was performed to detect any LEA-like characteristics of XhLEA3-2. Recombinant XhLEA3-2 was produced in Escherichia coli, purified, and used to generate XhLEA3-2 specific antibodies for expression analyses. The ability of XhLEA3-2 to function as a molecular chaperone was assessed using a lactate dehydrogenase (LDH) enzyme stability assay. Transgenic expression of XhLEA3-2 in E. coli and tobacco was also investigated. In summary, this thesis demonstrates that XhLEA3-2: has typical LEA protein properties according to bioinformatic analyses, has two close homologs in X. viscosa, is present in dry X. humilis leaf tissue, has homologs present in dry X. viscosa leaf tissue, has some molecular chaperone activity, can protect E. coli from desiccation but not from osmotic stress, and can be transiently expressed in tobacco. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Molecular and Cell Biology en_ZA
dc.title The functional analysis of XhLEA3-2 - a LEA_4 from the resurrection plant, Xerophyta humilis en_ZA
dc.type Master Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Department of Molecular and Cell Biology en_ZA
dc.type.qualificationlevel Masters
dc.type.qualificationname MSc en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Dennis, T. J. (2017). <i>The functional analysis of XhLEA3-2 - a LEA_4 from the resurrection plant, Xerophyta humilis</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Molecular and Cell Biology. Retrieved from http://hdl.handle.net/11427/27094 en_ZA
dc.identifier.chicagocitation Dennis, Timothy James. <i>"The functional analysis of XhLEA3-2 - a LEA_4 from the resurrection plant, Xerophyta humilis."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Molecular and Cell Biology, 2017. http://hdl.handle.net/11427/27094 en_ZA
dc.identifier.vancouvercitation Dennis TJ. The functional analysis of XhLEA3-2 - a LEA_4 from the resurrection plant, Xerophyta humilis. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Molecular and Cell Biology, 2017 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/27094 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Dennis, Timothy James AB - Climate change is a pressing reality in the current era. Changing environmental conditions and limited water availability are associated with the loss of arable land in areas where farming has traditionally thrived. Thus, linked to climate change, is the risk of a global food shortage. Resurrection plants are phenomenal in that they are able to survive extended periods of drought in a state of anhydrobiosis and then resume full metabolism upon rehydration. These plants serve as models to scientists and genetic engineers who hope to replicate, to a degree, the 'resurrection phenomenon' in drought sensitive crop species. The ability of resurrection plants to survive drought needs to be studied on a molecular level if it is to be implemented in transgenic crops. Currently, the molecular mechanisms of desiccation tolerance are only somewhat understood, and considerable investigation is still required. Xerophyta humilis is a monocotyledonous resurrection plant in which one of the responses to extreme water loss is the upregulation of several Late Embryogenesis Abundant (LEA) genes. The protein products of these genes, called LEA proteins, are known to be correlated with abiotic stress tolerance in plants, invertebrates and microorganisms. However, the precise molecular mode(s) of action of LEA proteins are still poorly understood. In this study, a group LEA_4, LEA protein, which we have termed XhLEA3-2, shown to be transcriptionally upregulated during desiccation of the resurrection plant X. humilis, has been characterized. A bioinformatic, predictive analysis was performed to detect any LEA-like characteristics of XhLEA3-2. Recombinant XhLEA3-2 was produced in Escherichia coli, purified, and used to generate XhLEA3-2 specific antibodies for expression analyses. The ability of XhLEA3-2 to function as a molecular chaperone was assessed using a lactate dehydrogenase (LDH) enzyme stability assay. Transgenic expression of XhLEA3-2 in E. coli and tobacco was also investigated. In summary, this thesis demonstrates that XhLEA3-2: has typical LEA protein properties according to bioinformatic analyses, has two close homologs in X. viscosa, is present in dry X. humilis leaf tissue, has homologs present in dry X. viscosa leaf tissue, has some molecular chaperone activity, can protect E. coli from desiccation but not from osmotic stress, and can be transiently expressed in tobacco. DA - 2017 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2017 T1 - The functional analysis of XhLEA3-2 - a LEA_4 from the resurrection plant, Xerophyta humilis TI - The functional analysis of XhLEA3-2 - a LEA_4 from the resurrection plant, Xerophyta humilis UR - http://hdl.handle.net/11427/27094 ER - en_ZA


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