"Plant seeds are responsible for most of the world’s food supply and are important for the production of biofuels, fibers, and value-added chemicals. Seeds are also complex biological structures made of three genetically different tissues: the embryo, the endosperm that has nourishing functions and the seed coat that interfaces with the environment. The seed coat of the model plant Arabidopsis thaliana can be divided into five structurally different layers. The innermost layer, the endothelium, accumulates proanthocyanidins, strong antioxidant compounds that create a protective chemical and physical barrier, and coordinates seed growth in concert with the endosperm, embryo and other seed coat layers. From an applied perspective, the endothelium is responsible for the important agronomic trait of seed quality and growing evidence suggests that seed proanthocyanidins are beneficial for human health. Therefore, a deeper understanding of the molecular mechanisms underlying seed coat development might have profound scientific and practical implications.I propose a project aimed at elucidating the regulatory gene networks responsible for the development of the endothelium in A. thaliana. In order to achieve this goal, I propose to first dynamically profile the endothelium transcriptome through the INTACT method for individual cell types isolation. Second, I plan to start mapping regulatory gene networks by characterizing the downstream target genes of the TRANSPARENT TESTA 16 (TT16) transcription factor, known to play a key role in A. thaliana endothelium development. This study will be combined with a complementary analysis of TT16 protein complexes. Finally, the data obtained by each of the three project steps will be cross-analyzed in order to gain a broader understanding of the molecular processes underlying endothelium development and discover potentially novel genes involved in seed coat development to be further characterized."