UC San Diego

Abscisic Acid (ABA) is a phytohormone that is crucial for regulating the stress response pathway in plants. Accumulation of ABA can be triggered by many types of environmental stress, and buildup of ABA can cause changes in plant germination, the elongation and prioritization of primary and lateral root growth, and more. Though we know ABA is an extremely important hormone for plant stress response, we know little about the transcription factors involved in the ABA regulatory pathway. In this thesis we utilize two different sources of genetic diversity in Arabidopsis thaliana to investigate the transcription factors behind the ABA pathway. The first source of genetic diversity comes from artificial micro RNAs (amiRNAs). By screening through a library of seeds containing amiRNAs that target transcription factors, we identified two transcription factors, AIF1 and AIF4, that we believe are involved in the ABA stress response pathway. The second source of genetic diversity comes from naturally occurring ecotypes of Arabidopsis thaliana found in various regions across the globe. By screening through seeds collected from different countries around the world, we found two lineages of Arabidopsis thaliana, one from Bikfaiya, Lebanon, and another from Ciry-le-Noble, France, that demonstrate ABA hypersensitivity compared to Col-0, the current standard for Arabidopsis thaliana research native to Columbia, Missouri, USA. By continuing to analyze these ecotypes of Arabidopsis thaliana, we may be able to discern what naturally occurring genetic variations granted the increased ABA sensitivity we observed during our experimentation.