title: Multiple facets of Arabidopsis seedling development require indole-3-butyric acid-derived auxin.
abstract: Levels of auxin, which regulates both cell division and cell elongation in plant development, are controlled by synthesis, inactivation, transport, and the use of storage forms. However, the specific contributions of various inputs to the active auxin pool are not well understood. One auxin precursor is indole-3-butyric acid (IBA), which undergoes peroxisomal β-oxidation to release free indole-3-acetic acid (IAA). We identified ENOYL-COA HYDRATASE2 (ECH2) as an enzyme required for IBA response. Combining the ech2 mutant with previously identified iba response mutants resulted in enhanced IBA resistance, diverse auxin-related developmental defects, decreased auxin-responsive reporter activity in both untreated and auxin-treated seedlings, and decreased free IAA levels. The decreased auxin levels and responsiveness, along with the associated developmental defects, uncover previously unappreciated roles for IBA-derived IAA during seedling development, establish IBA as an important auxin precursor, and suggest that IBA-to-IAA conversion contributes to the positive feedback that maintains root auxin levels.
authors.affiliation: Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA.
authors.forename: Lucia C
authors.initials: LC
authors.lastname: Strader
authors.forename: Dorthea L
authors.initials: DL
authors.lastname: Wheeler
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Christensen
authors.forename: John C
authors.initials: JC
authors.lastname: Berens
authors.forename: Jerry D
authors.initials: JD
authors.lastname: Cohen
authors.forename: Rebekah A
authors.initials: RA
authors.lastname: Rampey
authors.forename: Bonnie
authors.initials: B
authors.lastname: Bartel
mesh_terms: D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D002455:Cell Division; D002874:Chromosome Mapping; D004746:Enoyl-CoA Hydratase / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D007211:Indoles / Q000378:metabolism*; D009154:Mutation; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development*
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D007211:Indoles; D010937:Plant Growth Regulators; C014612:indolebutyric acid; C030737:indoleacetic acid; C515968:ECH2 protein, Arabidopsis; D004746:Enoyl-CoA Hydratase