RGF1 controls root meristem size through ROS signaling

Stem cell niche and root meristem size are maintained by intercellular interactions and signaling networks of a peptide hormone, Root Meristem Growth Factor 1 (RGF1). How RGF1 regulates root meristem development is an essential question to understand stem cell function. Although five receptors of RGF1 have been identified, the downstream signaling mechanism remains unknown. Here, we report a series of signaling events following RGF1 action. The RGF1-receptor pathway controls the distribution of reactive oxygen species (ROS) along the developmental zones of the Arabidopsis root. We identify a novel transcription factor, RGF1 INDUCIBLE TRANSCRIPTION FACTOR 1 (RITF1) that plays a central role in mediating RGF1 signaling. Manipulating RITF1 expression leads to redistribution of ROS along the root developmental zones. Changes in ROS distribution, in turn, enhance the stability of the PLETHORA2 (PLT2) protein, a master regulator of root stem cells. Our study, thus, clearly depicts a signaling cascade initiated by RGF1, linking the RGF1 peptide to ROS regulatory mechanisms.