CLE peptide signaling promotes root meristem maintenance and regeneration

Indeterminate growth of the root relies on the root apical meristem (RAM), which is maintained by its quiescent center (QC). The QC undergoes highly regulated divisions to maintain adjacent stem cells, and if the QC and its surrounding cells are heavily damaged or removed the youngest remaining cells will regenerate the RAM. Previously we found that cell-to-cell mobile CLAVATA3/ENDOSPERM SURROUNDING REGION-LIKE (CLE) peptides signal through the receptor kinases BARELY ANY MERISTEM (BAM) 1 and 2 to promote QC divisions. Here we show that CLE signaling through BAM1/2 is required for QC divisions via regulation of QC-active D-type cyclin accumulation. Moreover, single-nuclear RNA sequencing indicates that BAM1/2 are necessary for proper regulation of cell divisions in the root stem cell niche. Consistent with this, we find that CLE signaling through BAM1/2 is necessary for RAM regeneration, potentially through specific CLE peptides. Altogether this work provides novel insights into the signaling networks underlying RAM maintenance, and potentially how peptide pathways are modulated to facilitate regeneration.