Flowering plants produce seeds through sexual reproduction called “double fertilization,” a unique manner among organisms. In Arabidopsis, two sperm cells are functionally identical, and each fertilizes with either an egg or a central cell. The large part of the molecular scenario for double fertilization where two independent male-female gamete fusions are precisely progressed has not been unveiled.
A few fertilization regulators on the gamete plasma membrane have been identified. The GCS1/HAP2 and GEX2 are involved in membrane attachment and fusion, respectively, and DMP9 is known to be involved in egg cell fertilization. All these regulators are membrane proteins resident on the sperm cell surface. As a trial to find additional fertilization regulators, a transgenic plant line, in which the GCS1 variant protein lacking transmembrane region was expressed in the egg cell, was produced, and the GCS1-interacting proteins were purified and then subjected to proteome analysis. Among the identified proteins, we found analytical candidates that localize to the gamete membranes. In this congress, the progress of the analyses will be introduced.