Rapid Elimination of the Persistent Synergid through a Cell Fusion Mechanism

• The persistent synergid cell fuses with the endosperm after fertilization
• Synergid cytoplasm containing pollen tube attractants is diluted by the fusion
• FIS-PRC2 is involved in mitosis-associated synergid nuclear elimination
• Each female gamete independently controls the cell-fusion and ethylene signaling

SummaryIn flowering plants, fertilization-dependent degeneration of the persistent synergid cell ensures one-on-one pairings of male and female gametes. Here, we report that the fusion of the persistent synergid cell and the endosperm selectively inactivates the persistent synergid cell in Arabidopsis thaliana. The synergid-endosperm fusion causes rapid dilution of pre-secreted pollen tube attractant in the persistent synergid cell and selective disorganization of the synergid nucleus during the endosperm proliferation, preventing attractions of excess number of pollen tubes (polytubey). The synergid-endosperm fusion is induced by fertilization of the central cell, while the egg cell fertilization predominantly activates ethylene signaling, an inducer of the synergid nuclear disorganization. Therefore, two female gametes (the egg and the central cell) control independent pathways yet coordinately accomplish the elimination of the persistent synergid cell by double fertilization.

Graphical AbstractFigure optionsDownload high-quality image (248 K)Download as PowerPoint slide