title: Local evolution of seed flotation in Arabidopsis.
abstract: Arabidopsis seeds rapidly release hydrophilic polysaccharides from the seed coat on imbibition. These form a heavy mucilage layer around the seed that makes it sink in water. Fourteen natural Arabidopsis variants from central Asia and Scandinavia were identified with seeds that have modified mucilage release and float. Four of these have a novel mucilage phenotype with almost none of the released mucilage adhering to the seed and the absence of cellulose microfibrils. Mucilage release was modified in the variants by ten independent causal mutations in four different loci. Seven distinct mutations affected one locus, coding the MUM2 β-D-galactosidase, and represent a striking example of allelic heterogeneity. The modification of mucilage release has thus evolved a number of times independently in two restricted geographical zones. All the natural mutants identified still accumulated mucilage polysaccharides in seed coat epidermal cells. Using nuclear magnetic resonance (NMR) relaxometry their production and retention was shown to reduce water mobility into internal seed tissues during imbibition, which would help to maintain seed buoyancy. Surprisingly, despite released mucilage being an excellent hydrogel it did not increase the rate of water uptake by internal seed tissues and is more likely to play a role in retaining water around the seed.
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Susana
authors.initials: S
authors.lastname: Saez-Aguayo
authors.affiliation: INRA, UR 1268 Biopolymères Interactions Assemblages, INRA, Nantes, France; Irstea, UR TERE, CS 64427, Rennes, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Rondeau-Mouro
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Macquet
authors.affiliation: Department of Genetics and Plant Breeding, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
authors.forename: Ilkka
authors.initials: I
authors.lastname: Kronholm
authors.affiliation: INRA, UR 1268 Biopolymères Interactions Assemblages, INRA, Nantes, France.
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Ralet
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Berger
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Sallé
authors.affiliation: INRA, UR 1268 Biopolymères Interactions Assemblages, INRA, Nantes, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Poulain
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Granier
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Lucy
authors.initials: L
authors.lastname: Botran
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Loudet
authors.affiliation: Department of Genetics and Plant Breeding, Max Planck Institute for Plant Breeding Research, Cologne, Germany; Institute of Evolution and Biodiversity, University of Münster, Münster, Germany.
authors.forename: Juliette
authors.initials: J
authors.lastname: de Meaux
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Annie
authors.initials: A
authors.lastname: Marion-Poll
authors.affiliation: INRA, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR1318, Saclay Plant Sciences, Versailles, France.
authors.forename: Helen M
authors.initials: HM
authors.lastname: North
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation; D062087:Plant Mucilage / Q000235:genetics; D012639:Seeds / Q000235:genetics / Q000254:growth & development*; D014867:Water / Q000737:chemistry / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; D062087:Plant Mucilage; D014867:Water; D001616:beta-Galactosidase