title: What's the physiological role of domain II-less Aux/IAA proteins?
abstract: Arabidopsis has Aux/IAA proteins that lack domain II which is a binding site for the TIR1 auxin receptor. These proteins have been shown to be more stable than the canonical Aux/IAA proteins. We investigated the phenotypes of overexpression lines of domain II-less Aux/IAA proteins, IAA20 and IAA30, by the use of 35S promoter. The transgenic lines showed many aberrant phenotypes in auxin physiology. The most conspicuous phenotype was collapse of the root apical meristem as occurred in plt1 plt2 double mutants. Because IAA20 and IAA30 were early auxin-inducible and were expressed in the root apical meristem, they may have a physiological role in maintaining the stem cell niche of root, by keeping the activity of MP/ARF5 and NPH4/ARF7 at an acceptable level. On the other hand, domain-II less Aux/IAA proteins are not present in balck cottonwood tree or grapevine, suggesting wide diversification of Aux/IAA proteins in higher plants.
authors.affiliation: Division of Biosphere Science; Graduate School of Environmental Science; Hokkaido University; Sapporo, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Sato
authors.forename: Kotaro T
authors.initials: KT
authors.lastname: Yamamoto
references.citation: Nature. 2007 Oct 25;449(7165):1053-7
references.pmid: 17960244
references.citation: Proc Natl Acad Sci U S A. 2008 Feb 26;105(8):3151-6
references.pmid: 18287041
references.citation: EMBO J. 2005 May 18;24(10):1874-85
references.pmid: 15889151
references.citation: Genes Dev. 2002 Jul 1;16(13):1610-5
references.pmid: 12101120
references.citation: Plant Cell. 2006 Mar;18(3):699-714
references.pmid: 16489122
references.citation: Cell. 2004 Oct 1;119(1):109-20
references.pmid: 15454085
references.citation: Funct Integr Genomics. 2006 Jan;6(1):47-59
references.pmid: 16200395
references.citation: Nature. 2007 Apr 5;446(7136):640-5
references.pmid: 17410169
references.citation: Development. 1999 Feb;126(4):711-21
references.pmid: 9895319
references.citation: Proc Natl Acad Sci U S A. 2006 Feb 28;103(9):3468-73
references.pmid: 16492731
references.citation: Plant Cell. 2005 Jul;17(7):1908-25
references.pmid: 15937229
references.citation: Plant Physiol. 2004 Jul;135(3):1738-52
references.pmid: 15247399
references.citation: Nature. 2005 May 26;435(7041):446-51
references.pmid: 15917798
references.citation: Nature. 2005 May 26;435(7041):441-5
references.pmid: 15917797
references.citation: BMC Plant Biol. 2007 Nov 06;7:59
references.pmid: 17986329
references.citation: Science. 1997 Jun 20;276(5320):1865-8
references.pmid: 9188533