Dynamics at Different Scales: Hormonal Control in Oryza Sativa Root Circumnutation and Gene Regulation in Arabidopsis thaliana Cell Differentiation

Abstract

This research spans multiple scales—from the entire organism, down to the genes that created it.The first project, “Gene Dynamics in Tissue Development”, explores how stem cell differentiation depends on the dynamics of gene networks. In the Arabidopsis thaliana root, the SCARECROW (SCR) transcription factor is required for an asymmetric cell division of a stem cell, resulting in two daughter cells that acquire different fates and tissue identities. Although much research has developed the network topology for this division, the dynamics of this process remain unknown. A core feature of the GRN controlling this stem cell asymmetric division is the SCR positive feedback loop. This research develops a synthetic biology approach to systematically and precisely tune various dynamics of SCR protein accumulation. Thus, one can explore the role and function of this positive feedback loop in the developmental process of asymmetric division in the Arabidopsis root. The following project, “Organ Form for Function” details how organ function depends on cellular form and hormonal signals. As sessile organisms, plants must establish a firm foundation into the terrain wherever the seed lands. Roots, especially the primary root (a seed’s first root), are the only anchor into the terrain. With a multiscale investigation, we identified a molecular pathway required for circumnutation, the circular growth of the root tip. We found the cellular physiology and key hormonal cell signaling events driving this behavior.