| Summary: | Abiotic stress is highly detrimental to crop productivity worldwide. Research is key to meeting the challenges of modern agriculture in a sustainable and positive fashion. This thesis contributes to our understanding of plant stress responses by examining two molecular aspects of abiotic stress. The first part of the work focused on the Unfolded Protein Response (UPR), a general stress response mechanism triggered by the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum. The study was conducted with the model plant Arabidopsis and shed new light on key players in the pathway. An unconventional alternative splicing mechanism, similar to the one identified in other higher eukaryotes, was found to parallel the activation of an ER-resident chaperone. The data suggest that this event is important to alleviate cellular stress in response to adverse environmental conditions such as heat. Further understanding of this pathway will help to develop a more complete view of the mechanisms involved in this response. The second part of the work investigated the interaction between nitrogen limitation and drought at the transcriptional level. A genome-wide transcript profiling experiment was performed to provide a comprehensive view of the response to nitrogen and water limitation in corn. The main finding was the demonstration of a clear synergistic effect between both stresses, an effect that was unexpectedly as important as either stress applied alone. This study adds to our current knowledge of abiotic stress response in plants and should provide the groundwork necessary to build future strategies for crop enhancement.
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