OsERF27-OsPLT4 regulatory module and ROS equilibrium control temporospatial rice crown root patterning

In rice (Oryza sativa), the root architecture is heavily shaped by shoot-borne crown roots that arise from the phytomers at the stem base. Each phytomer typically generates two spatially distinct crown root populations - lower/proximal and upper/distal crown roots - that also emerge temporally, with the proximal roots forming first. The mechanisms that coordinate this temporospatial patterning, however, remain poorly understood. Here, we identify an AP2/ERF gene OsERF27 which is differentially expressed between proximal and distal crown root primordia and is specifically required for the timely development of proximal roots. We further show that OsPLT4 functions downstream of OsERF27, defining an OsERF27-OsPLT4 regulatory module that drives the outgrowth and emergence of proximal crown roots. Interestingly, we uncover a requirement for reactive oxygen species (ROS) homeostasis in crown root development: Loss-of-function mutants display disturbed ROS accumulation pattern and sensitized root formation to ROS perturbation, indicating that this module promotes root emergence by spatially maintaining optimal redox balance. Together, our findings reveal a multi-layered regulatory network that integrates genetic elements with positional cues with redox control to pattern distinct crown root populations. Our study highlights how localized developmental programmes scale to shape root system architecture for tuning plant form and function in grasses.