Roots are essential for plant growth and agricultural productivity because they anchor plants and absorb the water and nutrients needed to sustain development. Root growth and development require neighboring tissues to divide, expand, and mature in a coordinated manner; if this coordination fails, because plants are surrounded by interconnected cell walls, organs tear themselves apart as they grow and normal root growth breaks down. More broadly, understanding how distinct tissues communicate during organ growth remains a major unresolved question in developmental biology. This project will determine how plants coordinate growth and differentiation across tissues, using Arabidopsis thaliana roots as a model. Recent work has shown that disrupting hormone signaling in a single cell layer of the root can dramatically reshape the growth of neighboring layers and halt root growth, confirming that developing tissues must communicate with each other to remain coordinated. To examine this communication, broad manipulation of plant hormone pathways in the whole plant often produces undesirable side effects, therefore understanding tissue-specific signaling, proposed here, is crucial for the precise engineering of crops. By uncovering the signals that maintain this coordination, the project will advance fundamental understanding of how multicellular plant organs grow and lay the foundation for precision plant engineering strategies to improve crop productivity, essential for food security. The project will also expand training in plant biology through a new undergraduate research course, a high school outreach project in plant genome engineering, and a training workshop on single-cell and spatial methods in plant biology. The project will test the hypothesis that organ development depends on molecular and mechanical feedback between neighboring tissues, such that perturbing hormone signaling in one cell layer dynamically reprograms both local and adjacent cell behaviors. R