Role of tomato BRANCHED1‐like genes in the control of shoot branching

• Published in: The Plant journal : for cell and molecular biology 2011-08, Vol.67 (4), p.701-714
• Main Authors: Martín‐Trillo, Mar, Grandío, Eduardo González, Serra, François, Marcel, Fabien, Rodríguez‐Buey, María Luisa, Schmitz, Gregor, Theres, Klaus, Bendahmane, Abdelhafid, Dopazo, Hernán, Cubas, Pilar
• Format: Article
• Language: English
• Subjects: Adaptations; Alternative splicing; Amino Acid Sequence; Angiosperms; Arabidopsis thaliana; Asteridae; Biological and medical sciences; BRANCHED1; Brassicaceae; Buds; Chromosome Mapping; duplication; Evolution; Evolution, Molecular; Evolutionary genetics; Fundamental and applied biological sciences. Psychology; Gene Duplication; Gene expression; Gene Expression Regulation, Plant - physiology; Genotype & phenotype; Life Sciences; Lycopersicon esculentum; Lycopersicon esculentum - genetics; Lycopersicon esculentum - growth & development; Lycopersicon esculentum - metabolism; Lycopersicon esculentum - ultrastructure; Molecular Sequence Data; Mutation; Phenotype; Phylogeny; Plant biology; Plant growth; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Leaves - ultrastructure; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Shoots - genetics; Plant Shoots - growth & development; Plant Shoots - metabolism; Plant Shoots - ultrastructure; Plants, Genetically Modified - genetics; Plants, Genetically Modified - growth & development; Plants, Genetically Modified - metabolism; Plants, Genetically Modified - ultrastructure; Point Mutation; RNA, Messenger - genetics; Rosidae; Sequence Alignment; shoot branching; Shoots; Solanaceae; Solanum; TCP genes; tomato; Tomatoes; Transcription Factors - genetics; Transcription Factors - metabolism; Vegetal Biology
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2011.04629.x

Summary 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.