title: The Genetic Basis of Composite Spike Form in Barley and 'Miracle-Wheat'.
abstract: Inflorescences of the tribe Triticeae, which includes wheat (Triticum sp. L.) and barley (Hordeum vulgare L.) are characterized by sessile spikelets directly borne on the main axis, thus forming a branchless spike. 'Compositum-Barley' and tetraploid 'Miracle-Wheat' (T. turgidum convar. compositum (L.f.) Filat.) display noncanonical spike-branching in which spikelets are replaced by lateral branch-like structures resembling small-sized secondary spikes. As a result of this branch formation 'Miracle-Wheat' produces significantly more grains per spike, leading to higher spike yield. In this study, we first isolated the gene underlying spike-branching in 'Compositum-Barley,' i.e., compositum 2 (com2). Moreover, we found that COM2 is orthologous to the branched head(t) (bh(t)) locus regulating spike branching in tetraploid 'Miracle-Wheat.' Both genes possess orthologs with similar functions in maize BRANCHED SILKLESS 1 (BD1) and rice FRIZZY PANICLE/BRANCHED FLORETLESS 1 (FZP/BFL1) encoding AP2/ERF transcription factors. Sequence analysis of the bh(t) locus in a collection of mutant and wild-type tetraploid wheat accessions revealed that a single amino acid substitution in the DNA-binding domain gave rise to the domestication of 'Miracle-Wheat.' mRNA in situ hybridization, microarray experiments, and independent qRT-PCR validation analyses revealed that the branch repression pathway in barley is governed through the spike architecture gene Six-rowed spike 4 regulating COM2 expression, while HvIDS1 (barley ortholog of maize INDETERMINATE SPIKELET 1) is a putative downstream target of COM2. These findings presented here provide new insights into the genetic basis of spike architecture in Triticeae, and have disclosed new targets for genetic manipulations aiming at boosting wheat's yield potential.
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Naser
authors.initials: N
authors.lastname: Poursarebani
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Seidensticker
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Ravi
authors.initials: R
authors.lastname: Koppolu
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Corinna
authors.initials: C
authors.lastname: Trautewig
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Piotr
authors.initials: P
authors.lastname: Gawroński
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Federica
authors.initials: F
authors.lastname: Bini
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Geetha
authors.initials: G
authors.lastname: Govind
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Twan
authors.initials: T
authors.lastname: Rutten
authors.affiliation: National Institute of Agrobiological Sciences, Plant Genome Research Unit, Tsukuba 305 8602, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Sakuma
authors.affiliation: National Institute of Agrobiological Sciences, Plant Genome Research Unit, Tsukuba 305 8602, Japan.
authors.forename: Akemi
authors.initials: A
authors.lastname: Tagiri
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Gizaw M
authors.initials: GM
authors.lastname: Wolde
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany Faculty of Agriculture, Cairo University, 12613 Giza, Egypt.
authors.forename: Helmy M
authors.initials: HM
authors.lastname: Youssef
authors.affiliation: John Innes Centre, Department of Crop Genetics, Colney, Norwich, NR4 7UH, United Kingdom Biological Sciences, Middle East Technical University, Cankaya, 06800, Ankara, Turkey.
authors.forename: Abdulhamit
authors.initials: A
authors.lastname: Battal
authors.affiliation: Parco Tecnologico Padano, 26900 Lodi, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Ciannamea
authors.affiliation: Parco Tecnologico Padano, 26900 Lodi, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Fusca
authors.affiliation: Plant Genome and Systems Biology, Helmholtz Center Munich, D-85764, Neuherberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Nussbaumer
authors.affiliation: Parco Tecnologico Padano, 26900 Lodi, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Pozzi
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Börner
authors.affiliation: Nordic Genetic Resource Center, SE-230 53 Alnarp, Sweden.
authors.forename: Udda
authors.initials: U
authors.lastname: Lundqvist
authors.affiliation: National Institute of Agrobiological Sciences, Plant Genome Research Unit, Tsukuba 305 8602, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Komatsuda
authors.affiliation: Dipartimento di Scienze Agrarie, University of Bologna, 40127 Bologna, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Salvi
authors.affiliation: Dipartimento di Scienze Agrarie, University of Bologna, 40127 Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tuberosa
authors.affiliation: John Innes Centre, Department of Crop Genetics, Colney, Norwich, NR4 7UH, United Kingdom.
authors.forename: Cristobal
authors.initials: C
authors.lastname: Uauy
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany.
authors.forename: Nese
authors.initials: N
authors.lastname: Sreenivasulu
authors.affiliation: Parco Tecnologico Padano, 26900 Lodi, Italy Università degli Studi di Milano, DiSAA, I-20133 Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Rossini
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, D-06466 Stadt Seeland, Germany thor@ipk-gatersleben.de.
authors.forename: Thorsten
authors.identifier: http://orcid.org/0000-0002-5267-0677
authors.initials: T
authors.lastname: Schnurbusch
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics* / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics*; D014908:Triticum / Q000235:genetics* / Q000648:ultrastructure
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors
keywords: inflorescence branching; yield potential; ‘Compositum-Barley’; ‘Miracle-Wheat’; ‘Wunder-Weizen’