title: Ethylene signaling is required for synergid degeneration and the establishment of a pollen tube block.
abstract: In flowering plants, sperm cells are delivered by pollen tubes, which are attracted by two egg-cell-adjoining synergids. Successful fertilization terminates pollen tube attraction; however, the underlying mechanisms are not understood. Here, we show that the process of fertilization activates an EIN3- and EIN2-dependent ethylene-response cascade necessary for synergid cell death and the concomitant establishment of a pollen tube block. Microinjection of the ethylene precursor ACC into the female gametophyte or constitutive ethylene response results in premature synergid disintegration. This indicates that the requirement of fertilization for synergid degeneration and associated establishment of a pollen tube block can be bypassed by mimicking a postfertilization ethylene burst. Surprisingly, the persistent synergid in ethylene-hyposensitive plants adopts the molecular profile and cell-cycle regime of the biparental embryo-nourishing tissue, suggesting that ethylene signaling prevents the formation of an asexual maternal endosperm fraction.
authors.affiliation: Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany.
authors.forename: Ronny
authors.initials: R
authors.lastname: Völz
authors.forename: Juliane
authors.initials: J
authors.lastname: Heydlauff
authors.forename: Dagmar
authors.initials: D
authors.lastname: Ripper
authors.forename: Ludwig
authors.initials: L
authors.lastname: von Lyncker
authors.forename: Rita
authors.initials: R
authors.lastname: Groß-Hardt
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D016923:Cell Death; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D048750:Cell Nucleus Division; D004268:DNA-Binding Proteins; D056625:Endosperm / Q000166:cytology / Q000378:metabolism; D005030:Ethylenes / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D005306:Fertilization; D005453:Fluorescence; D017930:Genes, Reporter; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056771:Ovule / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D053205:Pollen Tube / Q000235:genetics / Q000378:metabolism*; D054817:Pollination; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D012100:Reproduction, Asexual; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C494589:EIL1 protein, Arabidopsis; C119963:EIN2 protein, Arabidopsis; C106987:EIN3 protein, Arabidopsis; D005030:Ethylenes; D009687:Nuclear Proteins; D011956:Receptors, Cell Surface; D014157:Transcription Factors; C036216:ethylene; C088137:aminoethoxyvinylglycine; D005998:Glycine