Dynamic control of lateral root positioning

- The root cap contains an auxin source that modulates lateral root patterning.
- Recurrent programmed cell death controls the regular spacing of lateral roots.
- Periodic release of auxin by dying root cap may trigger prebranch site formation.
- Tropic responses control the LR sidedness.

In dicot root systems, lateral roots are in general regularly spaced along the longitudinal axis of the primary root to facilitate water and nutrient uptake. Recently, recurrent programmed cell death in the root cap of the growing root has been implicated in lateral root spacing. The root cap contains an auxin source that modulates lateral root patterning. Periodic release of auxin by dying root cap cells seems to trigger lateral root specification at regular intervals. However, it is currently unclear through which molecular mechanisms auxin restricts lateral root specification to specific cells along the longitudinal and radial axes of the root, or how environmental signals impact this process.