Poster: Hormones

Abs # 587: Qualitative and quantitative analysis of indole-3-butyric acid conjugates in Arabidopsis thaliana

Presenter:	Vosberg, Anthony R., vosb0004@umn.edu
Authors	Vosberg, Anthony R. (A)   Cohen, Jerry D. (A)
Affiliations:	(A): University of Minnesota, Department of Horticultural Science

To date, studies concerning the identification of auxin conjugates have mainly focused on indole-3-acetic acid derivatives. Although some studies have focused on the products of applied indole-3-butyric acid (IBA) or on the effects of IBA conjugates, few studies have been concerned with the conjugation of naturally occurring IBA. The goal of this project is to qualitatively and quantitatively analyze the IBA conjugates in Arabidopsis thaliana. IBA concentrations will be analyzed in wild type (Columbia) A. thaliana as well as the pxal-1 mutant. The pxal-1 mutant has a putatively higher-than-normal concentration of IBA. Initially, tritiated IBA will be used in a feeding study to profile IBA conjugates formed in the plant. In order to carry out these studies, we are producing the tools necessary for modern analysis. For example, to avoid the nonspecific exchange of the tritium label, IBA will be labeled at the ring-5 position. 5-Br-IBA, to be used as a precursor for [5-³H]IBA, has been synthesized and confirmed by thin layer chromatography. We will next synthesize, using similar methods, the corresponding stable-isotope-labeled compounds (IBA and selected conjugates) to use as internal standards for quantitative analysis of IBA and its conjugates. Quantitation will be done by isotope dilution using gas chromatography-mass spectrometry. We thank Dr. Bonnie Bartel (Rice Univ.) for helpful advice and encouragement. This work is supported by a University of Minnesota Undergraduate Research Opportunity Program grant to ARV and by grant DE-A102-94ER20153 from the U.S. Department of Energy.