In recent years chromatin has emerged as an extremely dynamic platform for establishing and maintaining gene expression programs. Chemical alterations of DNA and histone proteins, nucleosome positioning and histone variant usage collectively allow the formation of complex combinatorial codes of chromatin modifications that determine local DNA accessibility to transcription and transcript processing machineries.As in animals, plant stem cell identity and lineage commitment are controlled by unique transcription factor networks and conserved chromatin factors including nucleosome remodelers, histone variants and histone modifiers of the Polycomb group (PcG, epigenetic repressors) as well as Trithorax group (TrxG, epigenetic activators). Moreover, in stem cells the histone variant H2A.Z collaborates with PcG factors and is pivotal for timely activation of differentiation genes during the transition to lineage commitment.Although more of these tantalizing concepts in the plant and animal chromatin field have recently surfaced non have hitherto been proven in vivo by studying specific cell types derived from developing organisms.I believe plants can become the next stepping-stone in our understanding of these developmental chromatin concepts. Due to lack of cell migration, easy supply of in vivo derived material as well as extensive collections of genetic backgrounds plants offer a unparalleled opportunity to study cell type specific chromatin changes along the trajectory of cell lineage commitment. I here propose to use Arabidopsis root development as a model system in combination with fluorescence assisted cell sorting, chromatin immuno-precipitation and genome-wide analysis of a set of chromatin parameters. This unique study will reveal parallels and diverging concepts of plant and animal development at the chromatin level and generate a deeper understanding of plant patterning processes that could lead to substantial crop improvements.