title: AXR2 encodes a member of the Aux/IAA protein family.
abstract: The dominant gain-of-function axr2-1 mutation of Arabidopsis causes agravitropic root and shoot growth, a short hypocotyl and stem, and auxin-resistant root growth. We have cloned the AXR2 gene using a map-based approach, and find that it is the same as IAA7, a member of the IAA (indole-3-acetic acid) family of auxin-inducible genes. The axr2-1 mutation changes a single amino acid in conserved domain II of AXR2/IAA7. We isolated loss-of-function mutations in AXR2/IAA7 as intragenic suppressors of axr2-1 or in a screen for insertion mutations in IAA genes. A null mutant has a slightly longer hypocotyl than wild-type plants, indicating that AXR2/IAA7 controls development in light-grown seedlings, perhaps in concert with other gene products. Dark-grown axr2-1 mutant plants have short hypocotyls and make leaves, suggesting that activation of AXR2/IAA7 is sufficient to induce morphological responses normally elicited by light. Previously described semidominant mutations in two other Arabidopsis IAA genes cause some of the same phenotypes as axr2-1, but also cause distinct phenotypes. These results illustrate functional differences among members of the Arabidopsis IAA gene family.
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, 27599-3280, USA.
authors.forename: P
authors.initials: P
authors.lastname: Nagpal
authors.forename: L M
authors.initials: LM
authors.lastname: Walker
authors.forename: J C
authors.initials: JC
authors.lastname: Young
authors.forename: A
authors.initials: A
authors.lastname: Sonawala
authors.forename: C
authors.initials: C
authors.lastname: Timpte
authors.forename: M
authors.initials: M
authors.lastname: Estelle
authors.forename: J W
authors.initials: JW
authors.lastname: Reed
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D001483:Base Sequence; D017931:DNA Primers; D007210:Indoleacetic Acids / Q000737:chemistry* / Q000235:genetics*; D009154:Mutation; D010641:Phenotype
chemical_list: D017931:DNA Primers; D007210:Indoleacetic Acids; C030737:indoleacetic acid