Functional Diversification of the Unfolded Protein Response in Arabidopsis

Much like a factory, the endoplasmic reticulum (ER) assembles simple cellular building blocks into complex molecular machines known as proteins. In order to protect the delicate protein folding process and ensure the proper cellular delivery of protein products under environmental stresses, eukaryotes have evolved a set of signaling mechanisms known as the unfolded protein response (UPR) to increase the folding capacity and resiliency of the ER. While the UPR is a conserved aspect of nearly all eukaryotic cells, this process is particularly important in plants, because their sessile nature commands adaptation for survival rather than escape from stress. As such, plants make special use of the UPR, and evidence indicates that the master regulators and downstream effectors of the UPR have distinct roles in mediating cellular processes that affect plant growth, development and stress responses. In my research I sought to contribute to the general knowledge of how the plant UPR is integrated with, and connected to other critical signal transduction mechanisms in stress and development. My work has helped to connect plant UPR activities with reactive oxygen species (ROS) signaling under canonical ER stress situations, by demonstrating that this ROS is required for ER stress survival. In collaboration with the National Aeronautics and Space Administration (NASA) I was able to explore the relevance of the UPR to spaceflight associated stress, and uncovered novel connections between the UPR and plant-specific abiotic stress responses. Finally, I establish a role for the UPR in the regulation of widely conserved metabolic signaling pathways, which are critical to maintain plant organ growth.