Key regulators of juvenile-to-adult phase change

The precise control of cell division orientation drives plant 3D structure formation, enabling radial and longitudinal growth. The SPL pathway is closely linked to age-related processes in the shoot, driving the vegetative transition from juvenile to adult phases by regulating specific morphological and molecular traits. Similarly, in the root apical meristem (RAM), SPL transcription factors orchestrate a comparable phase transition, highlighting their pivotal role in developmental shifts across both shoot and root systems. To identify key regulators, Yang et al. screened over 15,000 compounds using a high-throughput confocal imaging system. They identified a compound, coral7, that induces changes in cell division orientation by promoting expression of the transcription factor SPL13. The research team analyzed RAM development over time and found that late-stage roots undergo significant morphological changes, including middle cortex formation and meristem thickening, driven by reoriented cell divisions. SPL transcription factors were shown to regulate these processes by activating key cell division-related genes, such as CYCB1 and CYCD6;1, through the SHR pathway. Additionally, studies on monocot rice and its related spl mutants similarly revealed that SPL plays a key role in cell division orientation and root thickening in the rice root meristem. This demonstrates that SPL is a conserved gene responsible for remodeling root morphology (thickness) across plants. (Summary by Yuanyuan Liu @YuanyuanLiu12) Science 10.1126/science.ado4298