title: The FANTASTIC FOUR proteins influence shoot meristem size in Arabidopsis thaliana.
abstract: BACKGROUND
  Throughout their lives plants produce new organs from groups of pluripotent cells called meristems, located at the tips of the shoot and the root. The size of the shoot meristem is tightly controlled by a feedback loop, which involves the homeodomain transcription factor WUSCHEL (WUS) and the CLAVATA (CLV) proteins. This regulatory circuit is further fine-tuned by morphogenic signals such as hormones and sugars.
  
  
  RESULTS
  Here we show that a family of four plant-specific proteins, encoded by the FANTASTIC FOUR (FAF) genes, has the potential to regulate shoot meristem size in Arabidopsis thaliana. FAF2 and FAF4 are expressed in the centre of the shoot meristem, overlapping with the site of WUS expression. Consistent with a regulatory interaction between the FAF gene family and WUS, our experiments indicate that the FAFs can repress WUS, which ultimately leads to an arrest of meristem activity in FAF overexpressing lines. The finding that meristematic expression of FAF2 and FAF4 is under negative control by CLV3 further supports the hypothesis that the FAFs are modulators of the genetic circuit that regulates the meristem.
  
  
  CONCLUSIONS
  This study reports the initial characterization of the Arabidopsis thaliana FAF gene family. Our data indicate that the FAF genes form a plant specific gene family, the members of which have the potential to regulate the size of the shoot meristem by modulating the CLV3-WUS feedback loop.
authors.affiliation: Department of Molecular Biology, AG Schmid, Max Planck Institute for Developmental Biology, D-72076 Tübingen, Germany.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Wahl
authors.forename: Luise H
authors.initials: LH
authors.lastname: Brand
authors.forename: Ya-Long
authors.initials: YL
authors.lastname: Guo
authors.forename: Markus
authors.initials: M
authors.lastname: Schmid
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics*; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics; D017403:In Situ Hybridization; D018519:Meristem / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D020411:Oligonucleotide Array Sequence Analysis; D018520:Plant Shoots / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D058526:Plant Vascular Bundle / Q000235:genetics / Q000254:growth & development; D012097:Repressor Proteins / Q000235:genetics*
chemical_list: C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D012097:Repressor Proteins; C116421:WUSCHEL protein, Arabidopsis; D005966:Glucuronidase