Synthetic Programming of Combinatorial Gene Regulation in Plant Development

Specification and maintenance of cell identity relies on the complex interplay of transcription factors to generate diverse spatiotemporal patterns of gene expression. In Arabidopsis, the transcription factors SHORTROOT (SHR) and SCARECROW (SCR) are required for root radial patterning. Together they directly regulate CYCD6, a cell-cycle regulator, to orchestrate the formation of the ground tissue. Since SHR activates both SCR and CYCD6, the SHR-SCR-CYCD6 circuit forms a feed-forward loop (FFL), one of the most prevalent motifs in gene regulatory networks. Despite the overrepresentation of feed-forward loops in developmental networks, current understanding of FFL behavior is largely theoretical. To directly test feed-forward loop function in a developing plant, I am rewiring the native CYCD6 circuit and building a synthetic circuit to regulate CYCD6 in a feed-forward manner.