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.
Rogg
L E
LE
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005-1892.
Lasswell
J
J
Bartel
B
B
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