Multiple Facets of Arabidopsis Seedling Development Require Indole-3-Butyric Acid–Derived Auxin

Author Profile

Lucia Strader

Current Position: Postdoctoral Research Scientist, Biochemistry and Cell Biology, Rice University, Houston, Texas

Education: PhD in Molecular Plant Sciences, Washington State University, Pullman, Washington; BS in Agronomy, Louisiana State University, Baton Rouge, Louisiana

Non-scientific Interests: Baking, hiking, and scuba diving

I became interested in potential roles for auxin derived from indole-3-butyric acid (IBA) as I was studying mutants defective in the ATP-Binding Cassette (ABC) transporters ABCG36/PDR8 and ABCG37/PDR9. I found that these mutants, which inefficiently efflux IBA, displayed certain cell expansion phenotypes suggestive of elevated auxin levels. This made me wonder �V is IBA the normal source of auxin to drive these cell expansion processes? Examining previously identified mutants defective in the IBA-to-IAA conversion process revealed that they exhibited the reciprocal cell expansion phenotypes, suggesting that auxin levels may be decreased in these mutants. However, because I was not convinced that we had yet fully blocked the IBA-to-IAA conversion process, I expanded our mutant screen and identified enoyl coa hydratase2 (ech2), the subject of this paper, as an additional gene necessary for IBA ��-oxidation. I further found that I could strongly block IBA-to-IAA conversion by combining ech2 with other IBA ��-oxidation mutants, resulting in an array of auxin-related phenotypes and decreased auxin levels. Because these studies suggest that IBA plays larger roles in auxin biology than we would have anticipated, I will continue to study the roles of both IBA-to-IAA conversion and IBA transport in plant development as I start my independent laboratory this fall.