Gamete fusion is facilitated by two sperm cell-expressed DUF679 membrane proteins

Successful double fertilization in flowering plants relies on two coordinated gamete fusion events, but the underlying molecular processes are not well understood. We show that two sperm-specific DOMAIN OF UNKNOWN FUNCTION 679 membrane proteins (DMP8 and DMP9) facilitate gamete fusion, with a greater effect on sperm-egg fusion than on sperm-central cell fusion. We also show that sperm adhesion and sperm cell separation depend on egg cell-secreted EGG CELL 1 proteins