Role of Rop GTPases in Signaling during Male Gametophyte Development

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For plant seeds to develop, fertilization must occur, i.e., sperm cells from the male must unite with female cells in the embryo sac. Because the embryo sac is within the flower, the pollen tube of the male gametophyte must transport the sperm cells to this destination by navigating through several floral tissues. It accomplishes this crucial task by perceiving, interpreting and acting upon signals from the surrounding floral tissues. This project seeks to understand the mechanisms by which the male gametophyte develops and interacts with the flower and embryo sac to accomplish fertilization. The roles of a family of signaling proteins, the Rop GTPases, in coordinating the development of the male gametophyte will be investigated. This investigation will combine a genetic approach with molecular, cellular and bioinformatic methods, in two model plants, Arabidopsis thaliana and maize. Results from this work should establish roles for specific maize Rop GTPases in the distinct stages of male gametophyte development in vivo. Possible connections between A. thaliana pollen tube growth, Rop GTPases, and localized exocytosis may be elucidated and genes in maize and other grass crops that may influence Rop GTPase function may also be identified. This research may inspire new agriculturally-beneficial ways for controlling male gametophyte development, and thus plant reproduction, in maize and other closely-related crops (rice, wheat). For example, control of the male gametophyte could reduce unwanted gene flow from transgenic to non-transgenic plants. An outreach program to the Portland Public Schools will inform the public about pollen biology and bioinformatics. This program will allow high school students to participate in scientific research by helping to build a web-accessible database of broad interest to plant biologists.