title: Role of tomato BRANCHED1-like genes in the control of shoot branching.
abstract: In angiosperms, shoot branching greatly determines overall plant architecture and affects fundamental aspects of plant life. Branching patterns are determined by genetic pathways conserved widely across angiosperms. In Arabidopsis thaliana (Brassicaceae, Rosidae) BRANCHED1 (BRC1) plays a central role in this process, acting locally to arrest axillary bud growth. In tomato (Solanum lycopersicum, Solanaceae, Asteridae) we have identified two BRC1-like paralogues, SlBRC1a and SlBRC1b. These genes are expressed in arrested axillary buds and both are down-regulated upon bud activation, although SlBRC1a is transcribed at much lower levels than SlBRC1b. Alternative splicing of SlBRC1a renders two transcripts that encode two BRC1-like proteins with different C-t domains due to a 3'-terminal frameshift. The phenotype of loss-of-function lines suggests that SlBRC1b has retained the ancestral role of BRC1 in shoot branch suppression. We have isolated the BRC1a and BRC1b genes of other Solanum species and have studied their evolution rates across the lineages. These studies indicate that, after duplication of an ancestral BRC1-like gene, BRC1b genes continued to evolve under a strong purifying selection that was consistent with the conserved function of SlBRC1b in shoot branching control. In contrast, the coding sequences of Solanum BRC1a genes have evolved at a higher evolution rate. Branch-site tests indicate that this difference does not reflect relaxation but rather positive selective pressure for adaptation.
authors.affiliation: Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología/CSIC, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Martín-Trillo
authors.forename: Eduardo González
authors.initials: EG
authors.lastname: Grandío
authors.forename: François
authors.initials: F
authors.lastname: Serra
authors.forename: Fabien
authors.initials: F
authors.lastname: Marcel
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Rodríguez-Buey
authors.forename: Gregor
authors.initials: G
authors.lastname: Schmitz
authors.forename: Klaus
authors.initials: K
authors.lastname: Theres
authors.forename: Abdelhafid
authors.initials: A
authors.lastname: Bendahmane
authors.forename: Hernán
authors.initials: H
authors.lastname: Dopazo
authors.forename: Pilar
authors.initials: P
authors.lastname: Cubas
mesh_terms: D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D019143:Evolution, Molecular; D020440:Gene Duplication; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D017354:Point Mutation; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D014157:Transcription Factors