title: The barley Hooded mutation caused by a duplication in a homeobox gene intron.
abstract: In barley (Hordeum vulgare L.) the unit of inflorescence is the spikelet, which bears a fertile bract, the lemma, and the floret consisting of palea, two lodicules, three stamens and the pistil. The Hooded mutation causes the appearance of an extra flower of inverse polarity on the lemma. This phenotype is governed by the single dominant genetic locus K3. Here we show that the homeobox gene Knox3 represents this locus. Ectopic Knox3 gene expression in the primordium of the extra floret is caused by a 305-base pair duplication in intron 4, and phenocopies of the mutation are obtained in the heterologous tobacco system by Knox3 overexpression. It is concluded that homeotic genes of the Knox gene family are involved in floral evocation. Furthermore, the study of polarity of reproductive organs in K and related mutants can now focus on homeobox genes.
authors.affiliation: MPI für Züchtungsforschung, Köln, Germany.
authors.forename: K J
authors.initials: KJ
authors.lastname: Müller
authors.forename: N
authors.initials: N
authors.lastname: Romano
authors.forename: O
authors.initials: O
authors.lastname: Gerstner
authors.forename: F
authors.initials: F
authors.lastname: Garcia-Maroto
authors.forename: C
authors.initials: C
authors.lastname: Pozzi
authors.forename: F
authors.initials: F
authors.lastname: Salamini
authors.forename: W
authors.initials: W
authors.lastname: Rohde
mesh_terms: D000595:Amino Acid Sequence; D005801:Genes, Homeobox; D017343:Genes, Plant; D001467:Hordeum / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D010641:Phenotype; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D012150:Polymorphism, Restriction Fragment Length; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana