title: Deciphering the Role of POLYCOMB REPRESSIVE COMPLEX1 Variants in Regulating the Acquisition of Flowering Competence in Arabidopsis.
abstract: Polycomb group (PcG) proteins play important roles in regulating developmental phase transitions in plants; however, little is known about the role of the PcG machinery in regulating the transition from juvenile to adult phase. Here, we show that Arabidopsis (Arabidopsis thaliana) B lymphoma Moloney murine leukemia virus insertion region1 homolog (BMI1) POLYCOMB REPRESSIVE COMPLEX1 (PRC1) components participate in the repression of microRNA156 (miR156). Loss of AtBMI1 function leads to the up-regulation of the primary transcript of MIR156A and MIR156C at the time the levels of miR156 should decline, resulting in an extended juvenile phase and delayed flowering. Conversely, the PRC1 component EMBRYONIC FLOWER (EMF1) participates in the regulation of SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE and MIR172 genes. Accordingly, plants impaired in EMF1 function displayed misexpression of these genes early in development, which contributes to a CONSTANS-independent up-regulation of FLOWERING LOCUS T (FT) leading to the earliest flowering phenotype described in Arabidopsis. Our findings show how the different regulatory roles of two functional PRC1 variants coordinate the acquisition of flowering competence and help to reach the threshold of FT necessary to flower. Furthermore, we show how two central regulatory mechanisms, such as PcG and microRNA, assemble to achieve a developmental outcome.
authors.affiliation: Institute of Plant Biochemistry and Photosynthesis, Instituto de Bioquímica Vegetal y Fotosíntesis-Consejo Superior de Investigaciones Científicas-University of Seville, Isla de La Cartuja, 41092 Seville, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: Picó
authors.affiliation: Institute of Plant Biochemistry and Photosynthesis, Instituto de Bioquímica Vegetal y Fotosíntesis-Consejo Superior de Investigaciones Científicas-University of Seville, Isla de La Cartuja, 41092 Seville, Spain.
authors.forename: M Isabel
authors.identifier: http://orcid.org/0000-0003-3502-4849
authors.initials: MI
authors.lastname: Ortiz-Marchena
authors.affiliation: Institute of Plant Biochemistry and Photosynthesis, Instituto de Bioquímica Vegetal y Fotosíntesis-Consejo Superior de Investigaciones Científicas-University of Seville, Isla de La Cartuja, 41092 Seville, Spain.
authors.forename: Wiam
authors.initials: W
authors.lastname: Merini
authors.affiliation: Institute of Plant Biochemistry and Photosynthesis, Instituto de Bioquímica Vegetal y Fotosíntesis-Consejo Superior de Investigaciones Científicas-University of Seville, Isla de La Cartuja, 41092 Seville, Spain myriam.calonje@ibvf.csic.es.
authors.forename: Myriam
authors.identifier: http://orcid.org/0000-0001-6351-6774
authors.initials: M
authors.lastname: Calonje
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D063146:Polycomb-Group Proteins / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D029681:Arabidopsis Proteins; C435921:EMF1 protein, Arabidopsis; C418905:FT protein, Arabidopsis; D035683:MicroRNAs; C559759:Mirn156 microRNA, Arabidopsis; C543702:Mirn172 microRNA, Arabidopsis; D063146:Polycomb-Group Proteins