Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.

Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.

Targeting Efficient Photosynthesis in Crops Through Genetic Engineering

Timothy Taity Changa, University of Nebraska - Lincoln


The increasing demand for food, fiber, and bio-based industrial products will challenge agriculture production systems. To address this challenge to meet the expected future demand for agriculture production will require transformable innovations in both genetics and agronomic practices. Importantly the target of enhancing agricultural output is further confounded by climate change, and reduction of arable land. The overall goal of this research program was to use the tools of biotechnology with the aim to enhance and protect photosynthesis in sorghum (Sorghum bicolor L Moench) to mitigate the effects of abiotic stresses. The first strategy focused on the introduction of a putative inorganic carbon transporter B (ictB) from Synechococcus sp. and the sedoheptulose-1,7-bisphosphatase (SBPase) from tomato in sorghum. The two genes under the control of maize rbcs-1 promoter were introduced in sorghum via Agrobacterium-mediated gene transformation with ictB either targeted to the chloroplast or cytosol. Results from a subset transgenic events revealed a mitigation of photosynthesis compared to wild type under salt stress and during rehydration following water deficit in events with cytosolic targeted ictB. The second path, an evaluation of the Miscanthus X giganteus PPDK3 and PPDK4 promoter elements with and without their respective first introns was conducted via monitoring of the visual marker gene β-glucoronidase (GUS) in sorghum. Analysis of transgenic events revealed that the two promoter elements when directly fused to the reporter gene are incapable of driving the expression of GUS while a more constitutive expression profile was achieved when their respective introns are included. Additionally, cold induction of PPDK4 promoter was noted when a set of events derived from PPDK4-ppdk4::GUS were exposed to chilling temperature. Our findings add to the tool box of synthetic biology for improvement of targeted crop traits that can be imparted to mitigate the impacts of environmental stresses towards improved crop productivity.^

Subject Area


Recommended Citation

Changa, Timothy Taity, "Targeting Efficient Photosynthesis in Crops Through Genetic Engineering" (2017). ETD collection for University of Nebraska - Lincoln. AAI10615179.