Title page for ETD etd-05092005-112847

Document Type Master's Dissertation
Author Prins, Anneke
URN etd-05092005-112847
Document Title The protective role of oryzacystatin-1 under abiotic stress
Degree MSc(Botany)
Department Botany
Advisor Name Title
Prof K Kunert Committee Chair
Prof A-M Oberholster Committee Co-Chair
  • enzymes protection
  • crops effect of stress on
  • plants protection
Date 2003-09-05
Availability unrestricted
One of the most important photosynthetic enzymes in a plant is ribulose-1,5¬bisphosphate carboxylase/oxygenase (Rubisco), which plays a key role in carbon fixation. Degradation of this enzyme leads to decreased carbon fixation and poor photosynthetic performance by the plant. It is therefore of interest to investigate possible ways of protecting this enzyme during stress conditions in order to generate plants that would perform better under extreme climates. In this study the effect of an expressed, exogenous rice cysteine proteinase inhibitor (OCI) in transformed tobacco plants on Rubisco stability/content under chilling and senescence was investigated. Results showed that there is no significant protective role for exogenous OCI on the degradation/content of Rubisco when tobacco plants were exposed to chilling. This result was found using native gel-based quantification procedures, as well as immuno-blotting, spot densitometric analysis, and a radioactive quantification assay as analysis techniques. The study, however, provided evidence for protection of Rubisco against degradation by expression of OCI under a more severe stress condition, such as senescence using native gel-based quantification procedures as detection techniques. Tobacco plants were also transformed with a newly designed vector allowing expressed OCI to be transported to the chloroplast. Failure to detect so far any OCI-¬expressing transformed plants and the idea that delay of senescence could prove beneficial to farmers by providing a more nutrient-dense crop with higher tolerance against stress-induced cell death are discussed.

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Please cite as follows:

Prins, A 2003 The protective role of Oryzacystatin-1 under abiotic stress, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-05092005-112847/ >


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