The ChromAuxi project aims at understanding how the interplay between Auxin Response Factors (ARFs) and chromatin dynamics orchestrates the multiplicity of transcriptional responses to this phytohormone in Arabidopsis. First, we propose to determine using in vitro approaches the binding rules of the different classes of ARFs on genomic DNA and to characterize their mode of interaction with proteins affecting chromatin organization. Then, we will determine how the chromatin context influences the binding of ARFs along the genome and, conversely, how this binding affects chromatin accessibility in response to auxin. The functional significance of these molecular rules will be tested in planta using (epi)genome engineering methods. Decrypting auxin response at the ARF-chromatin interface should provide unprecedented insights into the principles governing the numerous yet specific auxin-triggered regulations that underpin most aspects of plant development.