2008 Eighth Annual Beckman Scholars Symposium
Saturday Poster Session - July 29, 2006

Abscisic acid (ABA) and auxin are phytohormones involved in the regulation of growth and development in plants. ABA stimulates stomatal closure, inhibits seed germination, and controls root growth. On the other hand, auxin regulates molecular processes such as cell elongation, cell division, and cell differentiation, as well as macroscopic processes like tropic responses, vascular development, lateral root formation, and apical dominance. ABA and auxin both inhibit root elongation, indicating that there may be interaction between the signaling pathways for the two hormones. Mutations in IBR5, a putative dual-specificity protein phosphatase, result in insensitivity to both auxin and ABA. In order to elucidate the connections between ABA and auxin signaling, ibr5 mutants were mutagenized with ethyl methyl sulfonate (EMS) to identify second-site modifiers, which carry new mutations that either suppress or enhance auxin response as seen in root growth. Our hypothesis is that cloning the genes defective in ibr5 suppressors and enhancers will unveil new links between the auxin and ABA signaling pathways.