Abstract Fink This proposal will identify the specific genes involved in pathway of IAA biosynthesis, the tissue specificity of these genes, the phenotypes of mutations that prevent expression, and regulatory mutations affecting the pathway. The plant hormone, indole acetic acid (IAA) has remarkably diverse effects on plant growth and morphogenesis (22) (e.g. apical dominance, cell division, cell enlargement and lateral root formation). Our belief is that once the gene(s) specifically involved in IAA biosynthesis are cloned, the role of internal IAA in each of these processes can be understood. As most of the structural genes in the pathway are found in multiple copies, mutations will be sought in each member of a set so that the role of gene redundancy in the tryptophan/IAA pathway can be determined. To achieve this goal experiments are designed to improve transformation, gene targeting, and the control of gene expression by antisense. %%% Indole acetic acid is a plant hormone which affects many growth and morphogenic characteristics of plants. Most of what is known have been determined by external application of IAA to plants. However, little is known about its synthesis and function in an in vivo situation. The aromatic amino acid pathway is utilized for the biosynthesis of IAA and we will identify and clone the genes encoding the enzymes of this pathway, determine gene copy number and attempt to gain insight into the internal functioning of the hormone. We will, as necessary, develop the technology needed to achieve these goals. ***
