It is clearly visible that after the trigger of an activation (black), one of the inhibitors (red) spreads rapidly. The other (green) spreads only slowly but remains for a longer period. New activations are possible only when the concentrations of both inhibitors become low enough (white regions).If the second antagonist has a moderate diffusion, alternating or pair-wise, 90°-rotated patterns are possible as well (Meinhardt et al., 1998
Recent observations have shown that the plant hormone auxin is required as a prerequisite in leaf initiation . Suppression of auxin transport suppresses leaf initiation, a situation that can be rescued by a local supply of auxin. This suggests that one of the expected antagonistic reactions results from a depletion
of auxin in a wider surrounding. The figure below shows snapshots of a corresponding simulation. Auxin is shown in gray, the long lasting inhibition in red. The upper row shows the coming and going of a signal to initiate a primordium. A new primordium appears when auxin concentration is high enough and the inhibitor low enough. The primordium remains localized due to a depletion of auxin in a wider region. The blue arrow points to the site of the least concentration of the long-lasting inhibitor, foreshadowing the position where the next leaf primordia will arise.