Non-canonical -mediated root branching contributes to plasticity in root system architecture.

Lateral roots (LRs), which originate from the growing root, and adventitious roots (ARs), which are formed from non-root organs, are the main contributors to the post-embryonic root system in However, our knowledge of how formation of the root system is altered in response to diverse inductive cues is limited. Here, we show that contributes to root system plasticity. When seedlings are grown vertically on medium, is not expressed in LR founder cells. During AR initiation, is expressed in AR founder cells and activates also functions in LR formation and is activated in that context by / and not by This indicates that divergent initial processes that lead to ARs and LRs may converge on a similar mechanism for primordium development. Furthermore, we demonstrated that when plants are grown in soil or upon wounding on medium, the primary root is able to produce both -mediated and non--mediated roots. The discovery of -mediated root-derived roots reveals a previously uncharacterized pathway that confers plasticity during the generation of root system architecture in response to different inductive cues.