title: Interactions of CUP-SHAPED COTYLEDON and SPATULA genes control carpel margin development in Arabidopsis thaliana.
abstract: A characteristic feature of flowering plants is the fusion of carpels, which results in the formation of an enclosed gynoecium. In Arabidopsis thaliana, the gynoecium is formed by the fusion of two carpels along their margins, which also act as a meristematic site for the formation of internal structures such as ovules, the septum and transmitting tract. How gene interactions coordinate the fusion and differentiation of the marginal structures during gynoecium development is largely unknown. It was previously shown that the SPATULA (SPT) gene is required for carpel fusion, whereas overexpression of the CUP-SHAPED COTYLEDON genes CUC1 and CUC2 prevents it. Here we provide evidence that SPT promotes carpel fusion in the apical gynoecium partly through the negative regulation of CUC1 and CUC2 expression. In spt, transcripts of both CUC genes accumulated ectopically, and addition of cuc1 and cuc2 mutations to spt suppressed the split phenotype of carpels specifically along their lateral margins. In the basal gynoecium, on the other hand, all three genes promoted the formation of margin-derived structures, as revealed by the synergistic interactions of spt with each of the cuc mutations. Our results suggest that differential interactions among SPT, CUC1 and CUC2 direct the formation of domain-specific structures of the Arabidopsis gynoecium.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192 Japan.
authors.forename: Most Altaf-Un
authors.initials: MA
authors.lastname: Nahar
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ishida
authors.forename: David R
authors.initials: DR
authors.lastname: Smyth
authors.forename: Masao
authors.initials: M
authors.lastname: Tasaka
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Aida
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D017930:Genes, Reporter; D017403:In Situ Hybridization; D008855:Microscopy, Electron, Scanning; D009154:Mutation; D010641:Phenotype; D025941:Protein Interaction Mapping; D050436:Regulatory Elements, Transcriptional
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; C426007:CUC1 protein, Arabidopsis; C107294:CUC2 protein, Arabidopsis; C426006:SPT protein, Arabidopsis