title: Insights from ANA-grade angiosperms into the early evolution of CUP-SHAPED COTYLEDON genes.
abstract: OBJECTIVE
  The closely related NAC family genes NO APICAL MERISTEM (NAM) and CUP-SHAPED COTYLEDON3 (CUC3) regulate the formation of boundaries within and between plant organs. NAM is post-transcriptionally regulated by miR164, whereas CUC3 is not. To gain insight into the evolution of NAM and CUC3 in the angiosperms, we analysed orthologous genes in early-diverging ANA-grade angiosperms and gymnosperms.
  
  
  METHODS
  We obtained NAM- and CUC3-like sequences from diverse angiosperms and gymnosperms by a combination of reverse transcriptase PCR, cDNA library screening and database searching, and then investigated their phylogenetic relationships by performing maximum-likelihood reconstructions. We also studied the spatial expression patterns of NAM, CUC3 and MIR164 orthologues in female reproductive tissues of Amborella trichopoda, the probable sister to all other flowering plants.
  
  
  RESULTS
  Separate NAM and CUC3 orthologues were found in early-diverging angiosperms, but not in gymnosperms, which contained putative orthologues of the entire NAM + CUC3 clade that possessed sites of regulation by miR164. Multiple paralogues of NAM or CUC3 genes were noted in certain taxa, including Brassicaceae. Expression of NAM, CUC3 and MIR164 orthologues from Am. trichopoda was found to co-localize in ovules at the developmental boundary between the chalaza and nucellus.
  
  
  CONCLUSIONS
  The NAM and CUC3 lineages were generated by duplication, and CUC3 was subsequently lost regulation by miR164, prior to the last common ancestor of the extant angiosperms. However, the paralogous NAM clade genes CUC1 and CUC2 were generated by a more recent duplication, near the base of Brassicaceae. The function of NAM and CUC3 in defining a developmental boundary in the ovule appears to have been conserved since the last common ancestor of the flowering plants, as does the post-transcriptional regulation in ovule tissues of NAM by miR164.
authors.affiliation: Laboratoire de Reproduction et Développement des Plantes, UMR 5667, CNRS-INRA-Université de Lyon, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Aurélie C M
authors.initials: AC
authors.lastname: Vialette-Guiraud
authors.forename: Hélène
authors.initials: H
authors.lastname: Adam
authors.forename: Cédric
authors.initials: C
authors.lastname: Finet
authors.forename: Sophie
authors.initials: S
authors.lastname: Jasinski
authors.forename: Stefan
authors.initials: S
authors.lastname: Jouannic
authors.forename: Charles P
authors.initials: CP
authors.lastname: Scutt
mesh_terms: D005075:Biological Evolution; D032462:Cycadopsida / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D030541:Databases, Genetic; D020440:Gene Duplication; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D017343:Genes, Plant / Q000235:genetics*; D019684:Magnoliopsida / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics*; D018519:Meristem / Q000235:genetics* / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics*; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant; D035683:MicroRNAs; D010940:Plant Proteins; D018749:RNA, Plant