title: Distinct subclades of Aux/IAA genes are direct targets of ARF5/MP transcriptional regulation.
abstract: The regulatory interactions between AUXIN RESPONSE FACTORS (ARFs) and Aux/IAA repressors play a central role in auxin signal transduction. Yet, the systems properties of this regulatory network are not well established. We generated a steroid-inducible ARF5/MONOPTEROS (MP) transgenic background to survey the involvement of this factor in the transcriptional regulation of the entire Aux/IAA family in Arabidopsis thaliana. Target genes of ARF5/MP identified by this approach were confirmed by chromatin immunoprecipitation, in vitro gel retardation assays and gene expression analyses. Our study shows that ARF5/MP is indispensable for the correct regulation of nearly one-half of all Aux/IAA genes, and that these targets coincide with distinct subclades. Further, genetic analyses demonstrate that the protein products of multiple Aux/IAA targets negatively feed back onto ARF5/MP activity. This work indicates that ARF5/MP broadly influences the expression of the Aux/IAA gene family, and suggests that such regulation involves the activation of specific subsets of redundantly functioning factors. These groups of factors may then act together to control various processes within the plant through negative feedback on ARF5. Similar detailed analyses of other Aux/IAA-ARF regulatory modules will be required to fully understand how auxin signal transduction influences virtually every aspect of plant growth and development.
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.|Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC, 20016, USA.
authors.forename: Naden T
authors.initials: NT
authors.lastname: Krogan
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Yin
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.
authors.forename: Wenzislava
authors.initials: W
authors.lastname: Ckurshumova
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.
authors.forename: Thomas
authors.initials: T
authors.lastname: Berleth
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D005810:Multigene Family; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D007210:Indoleacetic Acids; C111371:MONOPTEROS protein, Arabidopsis; D014157:Transcription Factors; C030737:indoleacetic acid; D003907:Dexamethasone
keywords: AUXIN RESPONSE FACTOR (ARF); Arabidopsis development; Aux/IAA genes; regulatory network; transcriptional regulation