Many auxin pathways – Roles for Multiple Auxin Biosynthetic Pathways (with Gary Gardner)

Biochemical and genetic studies of a number of higher plants have shown that the normal pathway for the production of indole-3-acetic acid (IAA) in seedlings is directly from indole by a tryptophan-independent pathway.   In contrast, a tryptophan dependent pathway for IAA biosynthesis has been shown to be operative in the first hours after a wounding stress.  These studies demonstrated that wounding alters in a transient way the route of IAA biosynthesis.  It is unknown which tryptophan-dependent pathway is activated by wounding or if the IAA produced following wounding has a discrete role that differentiates it form the IAA produced under normal growth conditions.

Thus, the objectives of this project are:

  1. Determine the effect of wounding on tryptophan-independent and different tryptophan-dependent pathways using stable isotope rapid kinetic labeling methods, gene expression analysis and enzyme protein quantification methods.
  2. Determine if stresses other than wounding alter the pathways used for IAA biosynthesis in normal and mutant plants.
  3. Determine, by specific labeling patterns, if the IAA that enters the polar transport system has a specific metabolic origin that differentiates it from the bulk of the IAA in the tissue under normal, wounding, and stress conditions.