title: The INDETERMINATE DOMAIN Protein BROAD LEAF1 Limits Barley Leaf Width by Restricting Lateral Proliferation.
abstract: Variation in the size, shape, and positioning of leaves as the major photosynthetic organs strongly impacts crop yield, and optimizing these aspects is a central aim of cereal breeding [1, 2]. Leaf growth in grasses is driven by cell proliferation and cell expansion in a basal growth zone [3]. Although several factors influencing final leaf size and shape have been identified from rice and maize [4-14], what limits grass leaf growth in the longitudinal or transverse directions during leaf development remains poorly understood. To identify factors involved in this process, we characterized the barley mutant broad leaf1 (blf1). Mutants form wider but slightly shorter leaves due to changes in the numbers of longitudinal cell files and of cells along the leaf length. These differences arise during primordia outgrowth because of more cell divisions in the width direction increasing the number of cell files. Positional cloning, analysis of independent alleles, and transgenic complementation confirm that BLF1 encodes a presumed transcriptional regulator of the INDETERMINATE DOMAIN family. In contrast to loss-of-function mutants, moderate overexpression of BLF1 decreases leaf width below wild-type levels. A functional BLF1-vYFP fusion protein expressed from the endogenous promoter shows a dynamic expression pattern in the shoot apical meristem and young leaf primordia. Thus, we propose that the BLF1 gene regulates barley leaf size by restricting cell proliferation in the leaf-width direction. Given the agronomic importance of canopy traits in cereals, identifying functionally different BLF1 alleles promises to allow for the generation of optimized cereal ideotypes.
authors.affiliation: Institut für Biochemie und Biologie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Jöst
authors.affiliation: Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK) Gatersleben, Corrensstrasse 3, 06466 Stadt Seeland, OT Gatersleben, Germany.
authors.forename: Götz
authors.initials: G
authors.lastname: Hensel
authors.affiliation: Institut für Biochemie und Biologie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Kappel
authors.affiliation: The James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK.
authors.forename: Arnis
authors.initials: A
authors.lastname: Druka
authors.affiliation: Institut für Biochemie und Biologie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany.
authors.forename: Adrien
authors.initials: A
authors.lastname: Sicard
authors.affiliation: Institut für Biochemie und Biologie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Hohmann
authors.affiliation: Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK) Gatersleben, Corrensstrasse 3, 06466 Stadt Seeland, OT Gatersleben, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Beier
authors.affiliation: Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK) Gatersleben, Corrensstrasse 3, 06466 Stadt Seeland, OT Gatersleben, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Himmelbach
authors.affiliation: The James Hutton Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK.
authors.forename: Robbie
authors.initials: R
authors.lastname: Waugh
authors.affiliation: Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK) Gatersleben, Corrensstrasse 3, 06466 Stadt Seeland, OT Gatersleben, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Kumlehn
authors.affiliation: Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK) Gatersleben, Corrensstrasse 3, 06466 Stadt Seeland, OT Gatersleben, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Stein
authors.affiliation: Institut für Biochemie und Biologie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam-Golm, Germany. Electronic address: michael.lenhard@uni-potsdam.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Lenhard
mesh_terms: D002455:Cell Division; D049109:Cell Proliferation; D015870:Gene Expression; D001467:Hordeum / Q000254:growth & development*; D009154:Mutation; D018515:Plant Leaves / Q000254:growth & development*; D010940:Plant Proteins / Q000378:metabolism*; D018520:Plant Shoots / Q000378:metabolism
chemical_list: D010940:Plant Proteins
keywords: BROAD LEAF1; INDETERMINATE DOMAIN protein; barley; leaf growth; leaf shape