During embryogenesis, a rigorous develomental program dominated by the plant hormone auxin, ensures the formation of a very predictably patterned embryonic root. After germination, auxin remains the key signals that steers root development. Its activity modulates directional growth, and the positioning and morphogenesis of lateral roots. Local, adverse environments, such as drought, or pathogens, are avoided by adjusting the root growth direction and branching pattern. The sensing of such adverse conditions often involves stress hormones such as jasmonic acid and abscisic acid that suppress auxin activities to modulate root growth. We found evidence that auxin modulates the activities of deeply conserved MOB1-NDR kinase complexes to suppress the root’s JA and ABA sensitivity. In this project, we will set out to test this hypothesis. First, we will test the effect of disrupting NDR function on root growth and lateral root development, and their hormonal sensitivity. Next, we will explore how auxin, JA and ABA affect NDR activity, and based on these findings we will develop a sensor for monitoring the NDR activities in a living root with cellular resolution. These analyses will allow to map hotspots of NDR activities relative to those of different hormones, and will help us understand the function of NDRs in hormonal-based fine-tuning of root growth regulation.