title: A positive signal from the fertilization of the egg cell sets off endosperm proliferation in angiosperm embryogenesis.
abstract: Double fertilization of the egg cell and the central cell by one sperm cell each produces the diploid embryo and the typically triploid endosperm and is one of the defining characteristics of flowering plants (angiosperms). Endosperm and embryo develop in parallel to form the mature seed, but little is known about the coordination between these two organisms. We characterized a mutation of the Arabidopsis thaliana Cdc2 homolog CDC2A (also called CDKA;1), which has a paternal effect. In cdc2a mutant pollen, only one sperm cell, instead of two, is produced. Mutant pollen is viable but can fertilize only one cell in the embryo sac, allowing for a genetic dissection of the double fertilization process. We observed exclusive fertilization of the egg cell by cdc2a sperm cells. Moreover, we found that unfertilized endosperm developed, suggesting that a previously unrecognized positive signal from the fertilization of the egg cell initiates proliferation of the central cell.
authors.affiliation: Unigruppe am Max-Planck-Institut für Züchtungsforschung, Max-Delbrück-Laboratorium, Lehrstuhl für Botanik III, Universität Köln, Carl-von-Linné-Weg 10, D-50829 Köln, Germany.
authors.forename: Moritz K
authors.initials: MK
authors.lastname: Nowack
authors.forename: Paul E
authors.initials: PE
authors.lastname: Grini
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Jakoby
authors.forename: Marcel
authors.initials: M
authors.lastname: Lafos
authors.forename: Csaba
authors.initials: C
authors.lastname: Koncz
authors.forename: Arp
authors.initials: A
authors.lastname: Schnittger
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D016203:CDC2 Protein Kinase / Q000235:genetics* / Q000378:metabolism; D019684:Magnoliopsida / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D011058:Pollen / Q000502:physiology*; D012639:Seeds / Q000166:cytology* / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D016203:CDC2 Protein Kinase; C418966:CDC2A protein, Arabidopsis