Figure 7.

Surface plasmon resonance and root-growth assay results confirm the numerical predictions. (a) The results from SPR experiments show that Trp (red line), ICA (green line), IBA (violet line) and IDA (olive line) do not bind TIR1 at all. Conversely, 1-NAA (magenta line), 2,4-D (cyan line) and IPA (orange line) all bind, although with differing activities from IAA (blue line). All compounds were tested at 50 µM. (b,c) Root-growth inhibition measurements substantially confirm these results, revealing that Trp (red squares), ICA (green triangles), IBA (violet triangles) and IDA (olive hexagons) do not inhibit root growth up to extreme concentrations. In (c), 1-NAA (magenta diamonds), 2,4-D (cyan triangles) and IPA (orange triangles) are all active auxins. Derived IC50 values are given in table 1.