title: BRANCHED1 promotes axillary bud dormancy in response to shade in Arabidopsis.
abstract: Plants interpret a decrease in the red to far-red light ratio (R:FR) as a sign of impending shading by neighboring vegetation. This triggers a set of developmental responses known as shade avoidance syndrome. One of these responses is reduced branching through suppression of axillary bud outgrowth. The Arabidopsis thaliana gene BRANCHED1 (BRC1), expressed in axillary buds, is required for branch suppression in response to shade. Unlike wild-type plants, brc1 mutants develop several branches after a shade treatment. BRC1 transcription is positively regulated 4 h after exposure to low R:FR. Consistently, BRC1 is negatively regulated by phytochrome B. Transcriptional profiling of wild-type and brc1 buds of plants treated with simulated shade has revealed groups of genes whose mRNA levels are dependent on BRC1, among them a set of upregulated abscisic acid response genes and two networks of cell cycle- and ribosome-related downregulated genes. The downregulated genes have promoters enriched in TEOSINTE BRANCHED1, CYCLOIDEA, and PCF (TCP) binding sites, suggesting that they could be transcriptionally regulated by TCP factors. Some of these genes respond to BRC1 in seedlings and buds, supporting their close relationship with BRC1 activity. This response may allow the rapid adaptation of plants to fluctuations in the ratio of R:FR light.
authors.affiliation: Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Cientificas, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: González-Grandío
authors.forename: César
authors.initials: C
authors.lastname: Poza-Carrión
authors.forename: Carlos Oscar S
authors.initials: CO
authors.lastname: Sorzano
authors.forename: Pilar
authors.initials: P
authors.lastname: Cubas
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002455:Cell Division; D016384:Consensus Sequence; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D017343:Genes, Plant; D008027:Light; D059372:Nucleotide Motifs; D010641:Phenotype; D051939:Phytochrome B / Q000235:genetics / Q000378:metabolism; D057445:Plant Dormancy; D011401:Promoter Regions, Genetic; D036226:Seedlings / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; C521259:BRC1 protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D014157:Transcription Factors; D051939:Phytochrome B