title: Endosperm cellularization defines an important developmental transition for embryo development.
abstract: The endosperm is a terminal seed tissue that is destined to support embryo development. In most angiosperms, the endosperm develops initially as a syncytium to facilitate rapid seed growth. The transition from the syncytial to the cellularized state occurs at a defined time point during seed development. Manipulating the timing of endosperm cellularization through interploidy crosses negatively impacts on embryo growth, suggesting that endosperm cellularization is a critical step during seed development. In this study, we show that failure of endosperm cellularization in fertilization independent seed 2 (fis2) and endosperm defective 1 (ede1) Arabidopsis mutants correlates with impaired embryo development. Restoration of endosperm cellularization in fis2 seeds by reducing expression of the MADS-box gene AGAMOUS-LIKE 62 (AGL62) promotes embryo development, strongly supporting an essential role of endosperm cellularization for viable seed formation. Endosperm cellularization failure in fis2 seeds correlates with increased hexose levels, suggesting that arrest of embryo development is a consequence of failed nutrient translocation to the developing embryo. Finally, we demonstrate that AGL62 is a direct target gene of FIS Polycomb group repressive complex 2 (PRC2), establishing the molecular basis for FIS PRC2-mediated endosperm cellularization.
authors.affiliation: Department of Biology and Zurich-Basel Plant Science Center, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Hehenberger
authors.forename: David
authors.initials: D
authors.lastname: Kradolfer
authors.forename: Claudia
authors.initials: C
authors.lastname: Köhler
mesh_terms: D017360:Arabidopsis / Q000196:embryology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D056625:Endosperm / Q000166:cytology* / Q000196:embryology*; D006601:Hexoses / Q000378:metabolism; D006652:Histological Techniques; D007091:Image Processing, Computer-Assisted; D026161:MADS Domain Proteins / Q000235:genetics / Q000378:metabolism*; D008853:Microscopy; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000502:physiology; D063146:Polycomb-Group Proteins; D016133:Polymerase Chain Reaction; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C560619:EDE1 protein, Arabidopsis; C117389:FIS2 protein, Arabidopsis; D006601:Hexoses; D026161:MADS Domain Proteins; D008869:Microtubule-Associated Proteins; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; D014157:Transcription Factors