A gain-of-function mutation in IAA28 suppresses lateral root development.
The phytohormone auxin is important in many aspects of plant development. We have isolated an auxin-resistant Arabidopsis mutant, iaa28-1, that is severely defective in lateral root formation and that has diminished adult size and decreased apical dominance. The iaa28-1 mutant is resistant to inhibition of root elongation by auxin, cytokinin, and ethylene, but it responds normally to other phytohormones. We identified the gene defective in the iaa28-1 mutant by using a map-based positional approach and found it to encode a previously uncharacterized member of the Aux/IAA gene family. IAA28 is preferentially expressed in roots and inflorescence stems, and in contrast to other Aux/IAA genes, IAA28 transcription is not induced by exogenous auxin. Studies of the gain-of-function iaa28-1 mutant suggest that IAA28 normally represses transcription, perhaps of genes that promote lateral root initiation in response to auxin signals.
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005-1892.
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Rogg
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Lasswell
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Bartel
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D002874:Chromosome Mapping; D003583:Cytokinins / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000494:pharmacology; D007211:Indoles / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development*; D018547:Plant Stems / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D012097:Repressor Proteins; D013045:Species Specificity; D014158:Transcription, Genetic
D003583:Cytokinins; D005030:Ethylenes; D007210:Indoleacetic Acids; D007211:Indoles; D012097:Repressor Proteins; C014612:indolebutyric acid; C036216:ethylene