title: The SEP4 gene of Arabidopsis thaliana functions in floral organ and meristem identity.
abstract: The ABC model of flower organ identity is widely recognized as providing a framework for understanding the specification of flower organs in diverse plant species. Recent studies in Arabidopsis thaliana have shown that three closely related MADS-box genes, SEPALLATA1 (SEP1), SEP2 and SEP3, are required to specify petals, stamens, and carpels because these organs are converted into sepals in sep1 sep2 sep3 triple mutants. Additional studies indicate that the SEP proteins form multimeric complexes with the products of the B and C organ identity genes. Here, we characterize the SEP4 gene, which shares extensive sequence similarity to and an overlapping expression pattern with the other SEP genes. Although sep4 single mutants display a phenotype similar to that of wild-type plants, we find that floral organs are converted into leaf-like organs in sep1 sep2 sep3 sep4 quadruple mutants, indicating the involvement of all four SEP genes in the development of sepals. We also find that SEP4 contributes to the development of petals, stamens, and carpels in addition to sepals and that it plays an important role in meristem identity. These and other data demonstrate that the SEP genes play central roles in flower meristem identity and organ identity.
authors.affiliation: Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, Department 0116, La Jolla, CA 92093, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Ditta
authors.forename: Anusak
authors.initials: A
authors.lastname: Pinyopich
authors.forename: Pedro
authors.initials: P
authors.lastname: Robles
authors.forename: Soraya
authors.initials: S
authors.lastname: Pelaz
authors.forename: Martin F
authors.initials: MF
authors.lastname: Yanofsky
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D035264:Flowers / Q000235:genetics* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D017403:In Situ Hybridization; D018519:Meristem / Q000235:genetics*; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009841:Oligonucleotides; D038081:Organogenesis / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D029681:Arabidopsis Proteins; D009841:Oligonucleotides; C496271:SEP4 protein, Arabidopsis thaliana