title: Genetic analysis of indole-3-butyric acid responses in Arabidopsis thaliana reveals four mutant classes.
abstract: Indole-3-butyric acid (IBA) is widely used in agriculture because it induces rooting. To better understand the in vivo role of this endogenous auxin, we have identified 14 Arabidopsis mutants that are resistant to the inhibitory effects of IBA on root elongation, but that remain sensitive to the more abundant auxin indole-3-acetic acid (IAA). These mutants have defects in various IBA-mediated responses, which allowed us to group them into four phenotypic classes. Developmental defects in the absence of exogenous sucrose suggest that some of these mutants are impaired in peroxisomal fatty acid chain shortening, implying that the conversion of IBA to IAA is also disrupted. Other mutants appear to have normal peroxisomal function; some of these may be defective in IBA transport, signaling, or response. Recombination mapping indicates that these mutants represent at least nine novel loci in Arabidopsis. The gene defective in one of the mutants was identified using a positional approach and encodes PEX5, which acts in the import of most peroxisomal matrix proteins. These results indicate that in Arabidopsis thaliana, IBA acts, at least in part, via its conversion to IAA.
authors.affiliation: Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA.
authors.forename: B K
authors.initials: BK
authors.lastname: Zolman
authors.forename: A
authors.initials: A
authors.lastname: Yoder
authors.forename: B
authors.initials: B
authors.lastname: Bartel
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers; D005020:Ethyl Methanesulfonate; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology; D007210:Indoleacetic Acids / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D000074435:Peroxisome-Targeting Signal 1 Receptor; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D016133:Polymerase Chain Reaction; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; D007210:Indoleacetic Acids; D007211:Indoles; C000590561:PEX5 protein, Arabidopsis; D000074435:Peroxisome-Targeting Signal 1 Receptor; D010937:Plant Growth Regulators; D018160:Receptors, Cytoplasmic and Nuclear; C014612:indolebutyric acid; C030737:indoleacetic acid; D005020:Ethyl Methanesulfonate