Precise transcriptional control of cellular quiescence by BRAVO/WOX5 complex in Arabidopsis roots

Understanding stem cell regulatory circuits is the next challenge in plant biology, as these cells are essential for tissue growth and organ regeneration in response to stress. In the Arabidopsis primary root apex, stem cell‐specific transcription factors BRAVO and WOX5 co‐localize in the quiescent centre (QC) cells, where they commonly repress cell division so that these cells can act as a reservoir to replenish surrounding stem cells, yet their molecular connection remains unknown. Genetic and biochemical analysis indicates that BRAVO and WOX5 form a transcription factor complex that modulates gene expression in the QC cells to preserve overall root growth and architecture. Furthermore, by using mathematical modelling we establish that BRAVO uses the WOX5/BRAVO complex to promote WOX5 activity in the stem cells. Our results unveil the importance of transcriptional regulatory circuits in plant stem cell development. SYNOPSIS The transcription factors BRAVO and WOX5 are essential regulators of stem cell division in Arabidopsis roots. Genetic analysis and mathematical modeling reveal BRAVO/WOX5 regulatory interactions and indicate mechanisms of stem cell control. The stem cell transcription factors BRAVO and WOX5 jointly promote quiescent center (QC) division in the Arabidopsis root apex. BRAVO and WOX5 mutually regulate their expression and form a protein complex that preserves quiescence at the root stem cell niche. Mathematical modelling uncovers precise regulatory circuits between BRAVO and WOX5 in plant stem cells. Graphical Abstract The transcription factors BRAVO and WOX5 are essential regulators of stem cell division in Arabidopsis roots. Genetic analysis and mathematical modeling reveal BRAVO/WOX5 regulatory interactions and indicate mechanisms of stem cell control.