Poster: Organelle Biogenesis

Abs # 1146: Genetic analysis of peroxisome biogenesis and function in Arabidopsis

Presenter:	Woodward, Andrew , drew@rice.edu
Authors	Woodward, Andrew  (A)   Zolman, Bethany K (A)   Bartel, Bonnie  (A)
Affiliations:	(A): Rice University

Plant peroxisomes are organelles that house a variety of functions, including fatty acid b-oxidation, peroxide metabolism, and photorespiration. Interestingly, fatty acid b-oxidation may be exclusively peroxisomal in plants, unlike in mammals where the task is divided between peroxisomes and mitochondria. Indole-3-butyric acid (IBA) is converted into the active auxin indole-3-acetic acid (IAA) in peroxisomes via a process that resembles fatty acid b-oxidation. To elucidate the function of IBA and the mechanism of its conversion to IAA, we have isolated mutants with reduced responses to exogenous IBA. These unbiased screens have yielded mutants with defects in fatty acid b-oxidation enzymes and potential peroxisome biogenesis (PEX) genes. In this way, IBA-responsiveness has proven to be a powerful assay for peroxisomal integrity. To further elucidate the biogenesis and function of plant peroxisomes, we are applying reverse-genetics techniques to isolate and characterize mutants defective in genes encoding putative PEX proteins. To establish the relevance of IBA conversion to IAA in plant development, we are employing DNA microarray analysis to examine any IBA-induced changes in gene expression in the IBA-response mutant pxa1, which is impaired in IBA to IAA conversion. Identification of genes involved in peroxisome biogenesis and IBA response will allow characterization of their roles in the formation and function of the plant peroxisome, an organelle of unique importance to plant development, hormonal signaling, and metabolism.