Class III homeodomain-leucine zipper (HD-ZIPIII) transcription factors promote important morphological attributes such as vascular patterning, outgrowth of the leaf blade, meristem formation and meristem size in plants. This project investigates mechanism through which HD-ZIPIII protein activity is modulated, extending Dr. Barton's recent discoveries that a new family of small proteins called LITTLE ZIPPERs are regulated by HD-ZIPIIIs transcriptionally, and regulate the activities of HD-ZIPIIIs through a feedback loop. The hypothesis that LITTLE ZIPPERs heterodimerize with the HD-ZIPIII proteins to either inhibit or alter their ability to bind DNA will be tested to probe the mechanism through which the LITTLE ZIPPERs inhibit HD-ZIPIII function. The native target sites for HD-ZIPIII binding in Arabidopsis LITTLE ZIPPER promoters will be identified. The consequence to the plant of loss of LITTLE ZIPPER activity will be determined. Finally, the binding of a hydrophobic ligand to the the HDZIPIII proteins is hypothesized and such ligands will be identified by screening a small chemical library. This project will directly widen our understanding of the regulation of plant development. Practical outcomes of this work include the ability to engineer desirable regulatory circuits and the potential to create plant varieties with desirable morphological features for the improvement of food and energy crops.The project will have a significant impact on K-12 and undergraduate education. The lab will train postdoctoral researchers, undergraduate and high school students in modern plant biology research.
