Reactive oxygen species act as signaling molecules to control root hair initiation and tip growth.

Root hairs (RHs) increase the surface area of roots, facilitating nutrient and water uptake and plant anchorage. RHs form from root epidermal cells and elongate by polar tip growth. Reactive oxygen species (ROS) have recently been implicated as important signals that drive RH formation and elongation using both genetic and imaging approaches. Localized changes in ROS levels in the RH tip are facilitated by hormone-mediated changes in the synthesis and activity of respiratory burst oxidase homologs and class III peroxidases. These findings broaden our understanding of the mechanisms controlling polar tip growth in plants that drive RH formation, which can inform the breeding and engineering of plants that thrive under drought and nutrient stress.