IOS-1021917 HAP2(GCS1): Mechanisms of double fertilization
The molecular mechanisms that allow gamete cells (sperm and egg) to fuse are unknown. Overcoming this gap in our knowledge is an important goal because gamete fusion is central to the life cycle of all sexually reproducing organisms. Flowering plants (including major crops like corn, rice, and soybean) undergo double fertilization: one sperm fuses with the egg cell to form an embryo and another sperm fuses with the central cell to produce endosperm, a specialized tissue that supports the embryo. These cell fusion events lead to formation of seeds, the basis of the human food system. Gaining greater understanding of gamete fusion in flowering plants will lead to technologies that can improve seed crop production and control reproduction of crop plants. The hap2-1 mutant was identified using genetic analysis in the model plant species Arabidopsis thaliana. hap2-1 mutant sperm appear normal, but fail to fuse with either the egg or the central cell. These mutants lack a protein, HAP2(GCS1), that is normally on the surface of sperm cells. The hypothesis that will be tested in this project is that the HAP2(GCS1) protein is directly involved in a process that allows the male and female gametes to fuse. The goals of this project are 1) to identify new proteins that participate with HAP2(GCS1) to mediate gamete fusion, 2) to identify proteins that regulate the function of HAP2(GCS1), and 3) to determine how HAP2(GCS1) and other proteins allow gamete cells to fuse. The results of this project will have broad scientific impacts because HAP2(GCS1) is found in many eukaryotic species and is likely part of a gamete fusion mechanism employed by many plants and animals. This project will provide cutting-edge research training for both female and male undergraduate, graduate, and post-doctoral researchers of diverse backgrounds. This project also includes an outreach component to local elementary and high school students and teachers.
