The Evolution of Gene Regulatory Networks that Confer Stress Tolerance to Arabidopsis and Arabidopsis-Related Species

All living organisms are exposed to constantly fluctuating environmental conditions and must rapidly respond to maintain homeostasis. While animals can escape adverse conditions, plants spend their entire lives in the same place and must respond appropriately to external environmental cues to survive. While most crop plants are sensitive to environmental stress, some wild relatives of domesticated crop plants harbor significant tolerance mechanisms. The sessile and diverse lifestyles of plants make them a valuable resource to better understand how organisms have evolved to cope with stress in their natural environments. I hypothesize that changes in gene regulation enable plants to adapt to environmental stress. My approach will be to explore how variation in the transcriptional network regulated by the plant hormone abscisic acid (ABA) modulates salt sensitivity in Arabidopsis accessions as well as other species within the Brassicaceae family. To test this, I aim to: (1) Examine the difference in physiological and transcriptional responsiveness in the root to NaCl between Arabidopsis and other, more salt tolerant, species within Brassicaceae. (2) Identify differences in transcription factor binding downstream of ABA signaling that confer differences in salt tolerance between species. (3) Determine if genomic polymorphisms contribute to variation in salt sensitivity within Arabidopsis. Understanding the molecular mechanisms that contribute to stress tolerance in plants will increase crop yields and reduce the cost of agricultural production.