title: An ancient and conserved function for Armadillo-related proteins in the control of spore and seed germination by abscisic acid.
abstract: Armadillo-related proteins regulate development throughout eukaryotic kingdoms. In the flowering plant Arabidopsis thaliana, Armadillo-related ARABIDILLO proteins promote multicellular root branching. ARABIDILLO homologues exist throughout land plants, including early-diverging species lacking true roots, suggesting that early-evolving ARABIDILLOs had additional biological roles. Here we investigated, using molecular genetics, the conservation and diversification of ARABIDILLO protein function in plants separated by c. 450 million years of evolution. We demonstrate that ARABIDILLO homologues in the moss Physcomitrella patens regulate a previously undiscovered inhibitory effect of abscisic acid (ABA) on spore germination. Furthermore, we show that A. thaliana ARABIDILLOs function similarly during seed germination. Early-diverging ARABIDILLO homologues from both P. patens and the lycophyte Selaginella moellendorffii can substitute for ARABIDILLO function during A. thaliana root development and seed germination. We conclude that (1) ABA was co-opted early in plant evolution to regulate functionally analogous processes in spore- and seed-producing plants and (2) plant ARABIDILLO germination functions were co-opted early into both gametophyte and sporophyte, with a specific rooting function evolving later in the land plant lineage.
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Moody
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Younousse
authors.initials: Y
authors.lastname: Saidi
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Gibbs
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Anushree
authors.initials: A
authors.lastname: Choudhary
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Holloway
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Eleanor F
authors.initials: EF
authors.lastname: Vesty
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Kiran Kaur
authors.initials: KK
authors.lastname: Bansal
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Bradshaw
authors.affiliation: School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
authors.forename: Juliet C
authors.identifier: 0000-0002-2381-0298
authors.initials: JC
authors.lastname: Coates
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism*; D051186:Armadillo Domain Proteins / Q000378:metabolism*; D019068:Bryopsida / Q000187:drug effects / Q000378:metabolism*; D017124:Conserved Sequence; D018525:Germination / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D010940:Plant Proteins / Q000378:metabolism*; D012639:Seeds / Q000187:drug effects / Q000378:metabolism*; D032503:Selaginellaceae / Q000187:drug effects / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013170:Spores / Q000378:metabolism
chemical_list: D051186:Armadillo Domain Proteins; D010940:Plant Proteins; D000040:Abscisic Acid
keywords: Arabidopsis thaliana; Armadillo proteins; abscisic acid (ABA); evolution; germination; moss; seed; spore