title: CCS52A2/FZR1, a cell cycle regulator, is an essential factor for shoot apical meristem maintenance in Arabidopsis thaliana.
abstract: BACKGROUND
  Cell division and cell fate decisions regulate organ formation and function in plant growth and development. It is still unclear how specific meristematic regulatory networks operate with the cell cycle machinery to translate stem cell identity and maintenance into cellular behavior. In this study, we address these questions by analysis of a shoot apex defective mutant, namely xcm9.
  
  
  RESULTS
  Phenotypic analysis of the xcm9 mutant reveals concomitant premature termination of floral shoots with frequent bifurcation of the shoot apices, stems, and flowers. Microscopic observations show irregular cell organization in shoot apical meristems of xcm9. Positional cloning revealed that xcm9 is a loss of function allele of the CCS52A2/FZR1 gene, which has previously been implicated in root development. Expression analysis demonstrated that CCS52A2 maintains a higher transcriptional expression level in actively dividing tissue. Genetic studies indicated that the CCS52A2 gene functions together with WUSCHEL (WUS) and CLAVATA3 (CLV3) in regulating the development of the shoot meristem, and also contributes to this regulation together with the chromatin remodeling pathway. In addition, fewer xcm9 cells express CYCLIN B1:1, showing that cell cycle progression is disrupted in the mutant.
  
  
  CONCLUSIONS
  We propose that the CCS52A2 gene is a mediator that functions together with meristematic genes to regulate meristem organization, and cross-functions with chromatin regulators in cell cycle progression during shoot apical meristem development.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, P.R, China.
authors.forename: Yajie
authors.initials: Y
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Ye
authors.forename: Beibei
authors.initials: B
authors.lastname: Li
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Zhou
authors.forename: Yuhai
authors.initials: Y
authors.lastname: Cui
authors.forename: Mark P
authors.initials: MP
authors.lastname: Running
authors.forename: Kede
authors.initials: K
authors.lastname: Liu
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D048429:Cell Size; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D018398:Homeodomain Proteins / Q000378:metabolism; D018519:Meristem / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics; D011003:Ploidies; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics
chemical_list: C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; C580758:CCS52A2 protein, Arabidopsis; D018797:Cell Cycle Proteins; D018398:Homeodomain Proteins; D012333:RNA, Messenger; C116421:WUSCHEL protein, Arabidopsis