title: Signals and prepatterns: new insights into organ polarity in plants.
abstract: The flattening of leaves results from the interaction between upper (adaxial) and lower (abaxial) domains in the developing primordium. These domains are specified by conserved, overlapping genetic pathways involving several distinct transcription factor families and small regulatory RNAs. Polarity determinants employ a series of antagonistic interactions to produce mutually exclusive cell fates whose positioning is likely refined by signaling across the adaxial-abaxial boundary. Signaling candidates include a mobile small RNA-the first positional signal described in adaxial-abaxial polarity. Possible mechanisms to polarize the incipient primordium are discussed, including meristem-derived signaling and a model in which a polarized organogenic zone prepatterns the adaxial-abaxial axis.
authors.affiliation: Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
authors.forename: Aman Y
authors.initials: AY
authors.lastname: Husbands
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Chitwood
authors.forename: Yevgeniy
authors.initials: Y
authors.lastname: Plavskin
authors.forename: Marja C P
authors.initials: MC
authors.lastname: Timmermans
mesh_terms: D019521:Body Patterning / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D016350:Leucine Zippers / Q000235:genetics; D019684:Magnoliopsida / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D035683:MicroRNAs / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D018749:RNA, Plant / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: D018398:Homeodomain Proteins; D035683:MicroRNAs; D018749:RNA, Plant; D015534:Trans-Activators