title: Arabidopsis PRC1 core component AtRING1 regulates stem cell-determining carpel development mainly through repression of class I KNOX genes.
abstract: Polycomb repressive complex 2 (PRC2)-catalyzed H3K27me3 marks are tightly associated with the WUS-AG negative feedback loop to terminate floral stem cell fate to promote carpel development, but the roles of Polycomb repressive complex 1 (PRC1) in this event remain largely uncharacterized.
  
  
  
  Here we show conspicuous variability in the morphology and number of carpels among individual flowers in the absence of the PRC1 core components AtRING1a and AtRING1b, which contrasts with the wild-type floral meristem consumed by uniform carpel production in Arabidopsis thaliana. Promoter-driven GUS reporter analysis showed that AtRING1a and AtRING1b display a largely similar expression pattern, except in the case of the exclusively maternal-preferred expression of AtRING1b, but not AtRING1a, in the endosperm. Indeterminate carpel development in the atring1a;atring1b double mutant is due to replum/ovule-to-carpel conversion in association with ectopic expression of class I KNOX (KNOX-I) genes. Moreover, AtRING1a and AtRING1b also play a critical role in ovule development, mainly through promoting the degeneration of non-functional megaspores and proper integument formation. Genetic interaction analysis indicates that the AtRING1a/b-regulated KNOX-I pathway acts largely in a complementary manner with the WUS-AG pathway in controlling floral stem cell maintenance and proper carpel development.
  
  
  
  Our study uncovers a novel mechanistic pathway through which AtRING1a and AtRING1b repress KNOX-I expression to terminate floral stem cell activities and establish carpel cell fate identities.
authors.affiliation: Institut de Biologie Moléculaire des Plantes (IBMP), UPR2357 du CNRS, Université de Strasbourg, 12 rue du Général ZIMMER, 67084, Strasbourg, France. chendh212@hunau.edu.cn.|College of Bioscience and Biotechnology, International Associated Laboratory of CNRS-Fudan-HUNAU on Plant Epigenome Research, Hunan Agricultural University, Changsha, 410128, China. chendh212@hunau.edu.cn.
authors.forename: Donghong
authors.initials: D
authors.lastname: Chen
authors.affiliation: Institut de Biologie Moléculaire des Plantes (IBMP), UPR2357 du CNRS, Université de Strasbourg, 12 rue du Général ZIMMER, 67084, Strasbourg, France.|Present address: Institut de Genetique et de Biologie Moleculaire et Cellulaire, 1 rue Laurent Fries, 67404, Illkirch, France.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Molitor
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Xu
authors.affiliation: Institut de Biologie Moléculaire des Plantes (IBMP), UPR2357 du CNRS, Université de Strasbourg, 12 rue du Général ZIMMER, 67084, Strasbourg, France. Wen-Hui.Shen@ibmp-cnrs.unistra.fr.
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Shen
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000254:growth & development; D017353:Gene Deletion; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000254:growth & development; D056771:Ovule / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D063150:Polycomb Repressive Complex 1 / Q000235:genetics / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology*
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D018398:Homeodomain Proteins; C405985:Knox1 protein, plant; D010940:Plant Proteins; C556677:RING1a protein, Arabidopsis; D063150:Polycomb Repressive Complex 1; C556678:RING1b protein, Arabidopsis
keywords: AtRING1; Carpel development; Floral stem cell; KNOX-I; Polycomb