For plants to grow and thrive, they must be able to obtain sufficient water and nutrients through their root system. Therefore, the development of appropriate root architecture - including the number and position of lateral branches - is key. Lateral branching is known to be regulated by auxin signalling, with periodic oscillations in auxin signalling being thought to prime specific sites for lateral root outgrowth. However, how this initial priming is converted into the generation of stable prebranch sites (PBSs) is poorly understood. Now, Kirsten ten Tusscher and colleagues explore this step of branching using a computational modelling approach. Building on an earlier model that explored the mechanisms underlying priming, they show that, by implementing an auxin-dependent increase in auxin signalling capacity alongside a chromatin-dependent memorisation of auxin levels over time, a transient priming signal can be converted into a stable PBS. Although the model has yet to be fully explored experimentally, the dynamics of this process in silico are consistent with what is observed in planta, and help to resolve previous contradictions in the literature about how auxin signalling regulates the spatiotemporal pattern of branching.
