Figure 3.

A, Logarithmic plot of [¹¹C]IAN levels after subcortical injection of tracer into the upper proximal zone of a nodal root (n = 5, control; n = 7, root herbivory). Results reflect first-order kinetics for [¹¹C]IAN metabolism and a strong root herbivore treatment effect with increased rate of substrate metabolism. B, Relative percent of [¹¹C]IAA product derived from [¹¹C]IAN metabolism shown in A. Herbivory increases the rate of [¹¹C]IAA formation, as well as increases loss of free [¹¹C]IAA from metabolism, conjugation, and/or receptor binding. C, Logarithmic plot of [¹¹C]IAM levels after subcortical injection of tracer into the upper proximal zone of a nodal root (n = 4, control; n = 4, root herbivory). Results show that [¹¹C]IAM is not metabolized in unstressed control roots but is actively metabolized in first-order kinetics after root herbivore treatment.