In Arabidopsis, lateral roots originate exclusively from cells located deep within the parental root. To facilitate organ emergence, the hormone auxin is hypothesised to originate from developing lateral roots, inducing expression of the auxin influx carrier LAX3 and cell-wall-separation enzymes in overlaying cells. The expression pattern of LAX3 is rather striking. Namely, LAX3 is expressed in just two adjacent files of cells in tissues overlaying new lateral roots, between which cells separate. To explore this, we developed a multiscale model that integrates information about the LAX3 network topology and auxin transport within realistic three-dimensional (3D) cell and tissue geometries. Surprisingly, we found that our original version of the model was not sufficient to capture the observed dynamics. By undergoing several iterations of the model-experiment cycle, we were able to identify the key components of the gene network model that were missing from our original description of the system.

This is a joint work with Benjamin Péret and Malcolm Bennett.