title: CORONA, PHABULOSA and PHAVOLUTA collaborate with BELL1 to confine WUSCHEL expression to the nucellus in Arabidopsis ovules.
abstract: Angiosperm ovules consist of three proximal-distal domains - the nucellus, chalaza and funiculus - demarcated by developmental fate and specific gene expression. Mutation in three paralogous class III homeodomain leucine zipper (HD-ZIPIII) genes leads to aberrations in ovule integument development. Expression of WUSCHEL (WUS) is normally confined to the nucellar domain, but in this triple mutant expression expands into the chalaza. MicroRNA-induced suppression of this expansion partially suppresses the effects of the HD-ZIPIII mutations on ovule development, implicating ectopic WUS expression as a component of the mutant phenotype. bell1 (bel1) mutants produce aberrant structures in place of the integuments and WUS is ectopically expressed in these structures. Combination of bel1 with the HD-ZIPIII triple mutant leads to a striking phenotype in which ectopic ovules emerge from nodes of ectopic WUS expression along the funiculi of the primary ovules. The synergistic phenotype indicates that BEL1 and the HD-ZIPIII genes act in at least partial independence in confining WUS expression to the nucellus and maintaining ovule morphology. The branching ovules of the mutant resemble those of some fossil gymnosperms, implicating BEL1 and HD-ZIPIII genes as players in the evolution of the unbranched ovule form in extant angiosperms.
authors.affiliation: School of Natural System, College of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan ptilo@mb.infoweb.ne.jp.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Yamada
authors.affiliation: School of Natural System, College of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sasaki
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan.
authors.forename: Kayo
authors.initials: K
authors.lastname: Hashimoto
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Nakajima
authors.affiliation: Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Gasser
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019521:Body Patterning / Q000235:genetics; D003583:Cytokinins / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D056771:Ovule / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D010641:Phenotype; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C097235:BEL1 protein, Arabidopsis; C000604553:CORONA protein, Arabidopsis; D003583:Cytokinins; D018398:Homeodomain Proteins; C114647:PHB protein, Arabidopsis; C114644:PHV protein, Arabidopsis; D014157:Transcription Factors; C116421:WUSCHEL protein, Arabidopsis
keywords: Arabidopsis thaliana; BEL1; Chalaza; HD-ZIPIII; Integument; Ovule; WUS