title: Co-option of the polarity gene network shapes filament morphology in angiosperms.
abstract: The molecular genetic mechanisms underlying abaxial-adaxial polarity in plants have been studied as a property of lateral and flattened organs, such as leaves. In leaves, laminar expansion occurs as a result of balanced abaxial-adaxial gene expression. Over- or under- expression of either abaxializing or adaxializing genes inhibits laminar growth, resulting in a mutant radialized phenotype. Here, we show that co-option of the abaxial-adaxial polarity gene network plays a role in the evolution of stamen filament morphology in angiosperms. RNA-Seq data from species bearing laminar (flattened) or radial (cylindrical) filaments demonstrates that species with laminar filaments exhibit balanced expression of abaxial-adaxial (ab-ad) genes, while overexpression of a YABBY gene is found in species with radial filaments. This result suggests that unbalanced expression of ab-ad genes results in inhibition of laminar outgrowth, leading to a radially symmetric structure as found in many angiosperm filaments. We anticipate that co-option of the polarity gene network is a fundamental mechanism shaping many aspects of plant morphology during angiosperm evolution.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA.
authors.forename: Ana Maria Rocha
authors.initials: AM
authors.lastname: de Almeida
authors.affiliation: 1] Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA [2] Institut de Systématique, Evolution et Biodiversité (UMR 7205 CNRS, Muséum National d'Histoire Naturelle, CP39, 16 rue Buffon, 75231 Paris Cedex 05, France.
authors.forename: Roxana
authors.initials: R
authors.lastname: Yockteng
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA.
authors.forename: James
authors.initials: J
authors.lastname: Schnable
authors.affiliation: 1] Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA [2] Laboratorio de Genética, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 3er Circuito Exterior Junto a Jardín Botánico, Coyoacán, México DF 04510.
authors.forename: Elena R
authors.initials: ER
authors.lastname: Alvarez-Buylla
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Freeling
authors.affiliation: 1] Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 USA [2] Department of Integrative Biology and The University and Jepson Herbaria, University of California, Berkeley, CA 94720 USA.
authors.forename: Chelsea D
authors.initials: CD
authors.lastname: Specht
mesh_terms: D005075:Biological Evolution; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D019684:Magnoliopsida / Q000033:anatomy & histology / Q000235:genetics*; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins