Figure 2.
Gamete attachment step, revealed by analyses of Arabidopsis fertilization mutants. GCS1- or GEX2-knockout sperm cells expressing sperm nucleus RFP (snRFP) were observed in ovules expressing egg membrane GFP (emGFP). The top panels depict 2 pairs of GCS1-knockout (gcs1) sperm cells released from 2 pollen tubes, most likely because the first pollen tube failed to fertilize and the second pollen tube, which was guided by the fertilization recovery system,16 similarly failed. All the unfused gcs1 sperm cells are attached to the egg cell. In contrast, GEX2-knockout (gex2–1) sperm cells occasionally detached from the egg cell (bottom panels, arrowhead). The scale bar represents 20 μm.