title: Functional conservation between CRABS CLAW orthologues from widely diverged angiosperms.
abstract: OBJECTIVE
  CRABS CLAW (CRC) encodes a transcription factor of the YABBY family that plays important roles in carpel and nectary development in Arabidopsis thaliana. Combined evolutionary and developmental studies suggest an ancestor of the CRC gene to have controlled carpel development in the last common ancestor of the angiosperms. Roles for CRC orthologues in leaf development and carpel specification in rice, and in nectary development in core eudicots, have accordingly been interpreted as derived. The aim of this study was to assess the capacity of CRC orthologues from a basal angiosperm and from rice to complement CRC mutants of arabidopsis. These experiments were designed to test the hypothesized ancestral role of CRC in the angiosperms, and to indicate whether putatively novel roles of various CRC orthologues resulted from changes to their encoded proteins, or from other molecular evolutionary events.
  
  
  METHODS
  The crc-1 mutant of arabidopsis was genetically transformed with the coding sequences of various CRC orthologues, and with paralogous YABBY coding sequences, under the control of the arabidopsis CRC promoter. The phenotypes of transformed plants were assessed to determine the degree of complementation of the crc-1 mutant phenotype in carpel fusion, carpel form and nectary development.
  
  
  RESULTS
  The CRC orthologue from the basal angiosperm Amborella trichopoda partially complemented the crc-1 mutant phenotype in carpels, but not in nectaries. The CRC orthologue from rice partially complemented all aspects of the crc-1 mutant phenotype. Though most non-CRC YABBY coding sequences did not complement crc-1 mutant phenotypes, YABBY2 (YAB2) proved to be an exception.
  
  
  CONCLUSIONS
  The data support a hypothesized ancestral role for CRC in carpel development and suggest that novel roles for CRC orthologues in monocots and in core eudicots resulted principally from molecular changes other than those affecting their coding sequences.
authors.affiliation: Laboratoire de Reproduction et Développement des Plantes, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Chloe
authors.initials: C
authors.lastname: Fourquin
authors.forename: Marion
authors.initials: M
authors.lastname: Vinauger-Douard
authors.forename: Pierre
authors.initials: P
authors.lastname: Chambrier
authors.forename: Annick
authors.initials: A
authors.lastname: Berne-Dedieu
authors.forename: Charles P
authors.initials: CP
authors.lastname: Scutt
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D019684:Magnoliopsida / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C119755:CRC protein, Arabidopsis; D018744:DNA, Plant; D014157:Transcription Factors; C121841:YABBY2 protein, Arabidopsis