IBR5, a dual-specificity phosphatase-like protein modulating auxin and abscisic acid responsiveness in Arabidopsis.
Auxin is an important plant hormone that plays significant roles in plant growth and development. Although numerous auxin-response mutants have been identified, auxin signal transduction pathways remain to be fully elucidated. We isolated ibr5 as an Arabidopsis indole-3-butyric acid-response mutant, but it also is less responsive to indole-3-acetic acid, synthetic auxins, auxin transport inhibitors, and the phytohormone abscisic acid. Like certain other auxin-response mutants, ibr5 has a long root and a short hypocotyl when grown in the light. In addition, ibr5 displays aberrant vascular patterning, increased leaf serration, and reduced accumulation of an auxin-inducible reporter. We used positional information to determine that the gene defective in ibr5 encodes an apparent dual-specificity phosphatase. Using immunoblot and promoter-reporter gene analyses, we found that IBR5 is expressed throughout the plant. The identification of IBR5 relatives in other flowering plants suggests that IBR5 function is conserved throughout angiosperms. Our results suggest that IBR5 is a phosphatase that modulates phytohormone signal transduction and support a link between auxin and abscisic acid signaling pathways.
Monroe-Augustus
Melanie
M
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA.
Zolman
Bethany K
BK
Bartel
Bonnie
B
D000040:Abscisic Acid / Q000494:pharmacology*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D054637:Dual-Specificity Phosphatases; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D000040:Abscisic Acid; D054637:Dual-Specificity Phosphatases; C483728:IBR5 protein, Arabidopsis; D017027:Protein Tyrosine Phosphatases