This proposal for a career development fellowship aims to assist a young researcher in achieving an independent position in the ERA. To reach this goal, we suggest the following project to decipher the molecular events taking place at plant chromatin during gene activation. Highly flexible plant cell fates allow life-long organogenesis, thus providing adequate models to study developmental processes. Differentiation of small stem cell clusters requires activation of developmental factors to follow proper temporal and spatial patterns. ULTRAPETALA 1 (ULT1) was identified by the hosting team as an activator of key genes involved in flower development of Arabidopsis thaliana.Our working hypothesis is that ULT1 induces transcription by functioning at the crossroads between transcription factors, transcriptional machinery and chromatin remodelers. This will be challenged by determining 1. ULT1 influence on repressive/activating histone mark abundance, respectively deposited by Polycomb/Trithorax group proteins, 2. ULT1 direct target genes and 3. ULT1 binding to chromatin during flower development with temporal resolution. We will employ next-generation sequencing (NGS) and computing methodologies, enabling in vitro determination of DNA binding sites and in vivo analysis of chromatin landscapes in Arabidopsis flowers for which genetic tools enable isolation of synchronised tissues in large amounts. This will permit correlating genome-wide ULT1 temporal binding patterns with changes in chromatin marks, transcriptional state of target genes and binding of putative ULT1 interactors and thus shed light on the chronology of events taking place at chromatin during transcriptional activation. Combined with the proposed training, including acquisition of new knowledge on epigenetics and flower development, analysis of NGS data and training in team and project management, the expected results and planned publications will provide a solid foundation for future career development.