title: Polar auxin transport is essential for medial versus lateral tissue specification and vascular-mediated valve outgrowth in Arabidopsis gynoecia.
abstract: Although it is generally accepted that auxin is important for the patterning of the female reproductive organ, the gynoecium, the flow as well as the temporal and spatial actions of auxin have been difficult to show during early gynoecial development. The primordium of the Arabidopsis (Arabidopsis thaliana) gynoecium is composed of two congenitally fused, laterally positioned carpel primordia bisected by two medially positioned meristematic regions that give rise to apical and internal tissues, including the ovules. This organization makes the gynoecium one of the most complex plant structures, and as such, the regulation of its development has remained largely elusive. By determining the spatiotemporal expression of auxin response reporters and localization of PINFORMED (PIN) auxin efflux carriers, we have been able to create a map of the auxin flow during the earliest stages of gynoecial primordium initiation and outgrowth. We show that transient disruption of polar auxin transport (PAT) results in ectopic auxin responses, broadened expression domains of medial tissue markers, and disturbed lateral preprocambium initiation. Based on these results, we propose a new model of auxin-mediated gynoecial patterning, suggesting that valve outgrowth depends on PIN1-mediated lateral auxin maxima as well as subsequent internal auxin drainage and provascular formation, whereas the growth of the medial domains is less dependent on correct PAT. In addition, PAT is required to prevent the lateral domains, at least in the apical portion of the gynoecial primordium, from obtaining medial fates.
authors.affiliation: Department of Plant Biology, Swedish University of Agricultural Sciences Uppsala BioCentre and Linnean Centre for Plant Biology in Uppsala, 756 51 Uppsala, Sweden (E.L., C.J.R., A.R.C., E.S.); andDepartment of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695 (R.G.F.) emma.larsson@slu.se eva.sundberg@slu.se.
authors.forename: Emma
authors.identifier: http://orcid.org/0000-0001-8042-8119
authors.initials: E
authors.lastname: Larsson
authors.affiliation: Department of Plant Biology, Swedish University of Agricultural Sciences Uppsala BioCentre and Linnean Centre for Plant Biology in Uppsala, 756 51 Uppsala, Sweden (E.L., C.J.R., A.R.C., E.S.); andDepartment of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695 (R.G.F.).
authors.forename: Christina J
authors.identifier: http://orcid.org/0000-0002-8116-0705
authors.initials: CJ
authors.lastname: Roberts
authors.affiliation: Department of Plant Biology, Swedish University of Agricultural Sciences Uppsala BioCentre and Linnean Centre for Plant Biology in Uppsala, 756 51 Uppsala, Sweden (E.L., C.J.R., A.R.C., E.S.); andDepartment of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695 (R.G.F.).
authors.forename: Andrea R
authors.initials: AR
authors.lastname: Claes
authors.affiliation: Department of Plant Biology, Swedish University of Agricultural Sciences Uppsala BioCentre and Linnean Centre for Plant Biology in Uppsala, 756 51 Uppsala, Sweden (E.L., C.J.R., A.R.C., E.S.); andDepartment of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695 (R.G.F.).
authors.forename: Robert G
authors.initials: RG
authors.lastname: Franks
authors.affiliation: Department of Plant Biology, Swedish University of Agricultural Sciences Uppsala BioCentre and Linnean Centre for Plant Biology in Uppsala, 756 51 Uppsala, Sweden (E.L., C.J.R., A.R.C., E.S.); andDepartment of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695 (R.G.F.) emma.larsson@slu.se eva.sundberg@slu.se.
authors.forename: Eva
authors.identifier: http://orcid.org/0000-0003-4228-434X
authors.initials: E
authors.lastname: Sundberg
mesh_terms: D017360:Arabidopsis / Q000196:embryology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D012098:Reproduction
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C116363:PIN1 protein, Arabidopsis; D010937:Plant Growth Regulators