Hormonal regulation of the leaf blade movement of Drosera capensis

Several Drosera species show a bending of the leaf blade as a slow reaction to a prey. In Drosera capensis L. this bending is enhanced by a simultaneous application of IAA either to the prey or to the leaf tip, and IAA alone can induce a curvature of the leaf. This curvature is always to the upper side of the leaf independent of the side of IAA application. PCIB (1 mM), and TIBA (0.1 mM) inhibit the bending reversibly. The inhibition by ABA (1 mM) is not reversible. A TIBA barrier between the prey and the tip of the leaf reduces the bending reaction, whereas application of TIBA to the basal part of the leaf has no effect. In the former case 35% of the leaves showed a strong bending just on the apical side of the TIBA barrier. It is concluded that the bending is a consequence of an internal auxin stream from the tip of the leaf to the bending point, induced by the prey.