Figure 3.

Schematic representation of the complexity generated by differential interaction in the auxin pathway machinery. Hypothetical interaction network of the AFB receptors with Aux/IAA proteins (A), Aux/IAAs with ARFs (B), and ARFs with different target genes (C) are shown as arrows. The thickness of lines indicates the affinity of the interaction. Further complexity is generated by feedback loops of Aux/IAA (D) and ARF (not drawn) expression. As shown, Aux/IAAs can directly repress their own transcription (right) or that of other Aux/IAAs (left). Note that the tissue-specific lack of one or more factors would change auxin responsiveness and target gene expression.