title: AGO1 controls arabidopsis inflorescence architecture possibly by regulating TFL1 expression.
abstract: OBJECTIVE
  The TERMINAL FLOWER 1 (TFL1) gene is pivotal in the control of inflorescence architecture in arabidopsis. Thus, tfl1 mutants flower early and have a very short inflorescence phase, while TFL1-overexpressing plants have extended vegetative and inflorescence phases, producing many coflorescences. TFL1 is expressed in the shoot meristems, never in the flowers. In the inflorescence apex, TFL1 keeps the floral genes LEAFY (LFY) and APETALA1 (AP1) restricted to the flower, while LFY and AP1 restrict TFL1 to the inflorescence meristem. In spite of the central role of TFL1 in inflorescence architecture, regulation of its expression is poorly understood. This study aims to expand the understanding of inflorescence development by identifying and studying novel TFL1 regulators.
  
  
  METHODS
  Mutagenesis of an Arabidopsis thaliana line carrying a TFL1::GUS (β-glucuronidase) reporter construct was used to isolate a mutant with altered TFL1 expression. The mutated gene was identified by positional cloning. Expression of TFL1 and TFL1::GUS was analysed by real-time PCR and histochemical GUS detection. Double-mutant analysis was used to assess the contribution of TFL1 to the inflorescence mutant phenotype.
  
  
  RESULTS
  A mutant with both an increased number of coflorescences and high and ectopic TFL1 expression was isolated. Cloning of the mutated gene showed that both phenotypes were caused by a mutation in the ARGONAUTE1 (AGO1) gene, which encodes a key component of the RNA silencing machinery. Analysis of another ago1 allele indicated that the proliferation of coflorescences and ectopic TFL1 expression phenotypes are not allele specific. The increased number of coflorescences is suppressed in ago1 tfl1 double mutants.
  
  
  CONCLUSIONS
  The results identify AGO1 as a repressor of TFL1 expression. Moreover, they reveal a novel role for AGO1 in inflorescence development, controlling the production of coflorescences. AGO1 seems to play this role through regulating TFL1 expression.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Fernández-Nohales
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Domenech
authors.affiliation: Institut Jean-Pierre Bourgin, UMR 1318, INRA, Route de St-Cyr, 78000 Versailles, France.
authors.forename: A E
authors.initials: AE
authors.lastname: Martínez de Alba
authors.affiliation: Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain.
authors.forename: J L
authors.initials: JL
authors.lastname: Micol
authors.affiliation: Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Alicante, Spain.
authors.forename: M R
authors.initials: MR
authors.lastname: Ponce
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain madueno@ibmcp.upv.es.
authors.forename: F
authors.initials: F
authors.lastname: Madueño
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060565:Argonaute Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D005966:Glucuronidase; D056626:Inflorescence / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development; D009154:Mutation; D010641:Phenotype
chemical_list: C117457:AGO1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D026161:MADS Domain Proteins; C102864:TFL1 protein, Arabidopsis; D005966:Glucuronidase
keywords: AGO1; ARGONAUTE1; Arabidopsis thaliana; Flower development; TERMINAL FLOWER 1; TFL1; flowering; inflorescence architecture; plant architecture