Non-canonical <i>WOX11</i>-mediated root branching contributes to plasticity in <i>Arabidopsis</i> root system architecture

Abstract

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 <i>Arabidopsis</i> However, our knowledge of how formation of the root system is altered in response to diverse inductive cues is limited. Here, we show that <i>WOX11</i> contributes to root system plasticity. When seedlings are grown vertically on medium, <i>WOX11</i> is not expressed in LR founder cells. During AR initiation, <i>WOX11</i> is expressed in AR founder cells and activates <i>LBD16</i><i>LBD16</i> also functions in LR formation and is activated in that context by <i>ARF7</i>/<i>19</i> and not by <i>WOX11</i> 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 <i>WOX11</i>-mediated and non-<i>WOX11</i>-mediated roots. The discovery of <i>WOX11</i>-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.