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

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 precurso...

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Bibliographic Details
Published in:The Plant cell 2011-03, Vol.23 (3), p.984-999
Main Authors: Strader, Lucia C., Wheeler, Dorthea L., Christensen, Sarah E., Berens, John C., Cohen, Jerry D., Rampey, Rebekah A., Bartel, Bonnie
Format: Article
Language:English
Subjects:
Acetic acid
Arabidopsis - growth & development
Arabidopsis - metabolism
Arabidopsis Proteins - metabolism
Auxins
Cell Division
Chromosome Mapping
Cotyledons
Enoyl-CoA Hydratase - metabolism
Enzymes
Hypocotyls
Inactivation
Indoleacetic Acids - metabolism
Indoles - metabolism
Insulin antibodies
Mutation
Phylogeny
Plant cells
Plant Growth Regulators - metabolism
Plant roots
Plant Roots - cytology
Plant Roots - growth & development
Plant Roots - metabolism
Plants
Root hairs
Seedlings
Seedlings - drug effects
Seedlings - growth & development
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Summary: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 ß-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.
ISSN:1040-4651
1532-298X
DOI:10.1105/tpc.111.083071