title: GRAMINIFOLIA promotes growth and polarity of Antirrhinum leaves.
abstract: The leaves of higher plants develop distinct cell types along their adaxial-abaxial (dorsal-ventral) axes. Interaction between leaf primordium cells with adaxial and abaxial identities is necessary for lateral growth of the developing leaf blade. We show that the growth and asymmetry of leaves in Antirrhinum majus involves the related YABBY transcription factors GRAMINIFOLIA (GRAM) and PROLONGATA (PROL). GRAM is expressed in abaxial margins of organ primordia where it promotes lateral growth and abaxial cell fate. GRAM, however, is not needed for abaxial fate in the absence of adaxial cell specification, suggesting that it promotes abaxial fate by excluding adaxial identity. Although GRAM expression is abaxially restricted, it functions redundantly with its abaxially expressed paralogue, PROL, and with the ubiquitously expressed PHANTASTICA gene to promote adaxial identity via intercellular signalling. This non cell-autonomous behaviour is consistent with the ability of GRAM in only the abaxial most cell layer to direct normal development of more adaxial cells. The contrasting roles of GRAM in promoting and inhibiting adaxial identity might serve to reinforce and maintain the distinction between adaxial and abaxial domains in the growing leaf primordium.
authors.affiliation: Institute of Cell and Molecular Biology, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, UK.
authors.forename: John F
authors.initials: JF
authors.lastname: Golz
authors.forename: Mario
authors.initials: M
authors.lastname: Roccaro
authors.forename: Robert
authors.initials: R
authors.lastname: Kuzoff
authors.forename: Andrew
authors.initials: A
authors.lastname: Hudson
mesh_terms: D032161:Antirrhinum / Q000235:genetics / Q000254:growth & development*; D035264:Flowers / Q000166:cytology / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D017403:In Situ Hybridization; D009024:Morphogenesis; D010802:Phylogeny; D018515:Plant Leaves / Q000166:cytology / Q000254:growth & development*; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors