Auxin Auxin Index to this page Auxin 1. Apical dominance 4. Fruit development 5. Weed Killers Auxins are plant hormones . The direction of light is detected at the tip of the shoot.
Blue light is most effective.
It is absorbed by a flavoprotein called phototropin . Flavoproteins contain flavin as a prosthetic group . Auxin is synthesized at the tip and translocated down along the shady side of the shoot. Auxin stimulates elongation of the cells on the shady side causing the shoot to bend toward the light. Link to some of the experiments that led to these conclusions.