The long-term goal of the proposed work is to understand the regulatory processes controlling development and function of the synergid cells. The two synergid cells are located within the seven-celled female gametophyte and are essential for the reproductive process in flowering plants. During the fertilization process, the pollen tube grows into one of the synergid cells, ceases growth, ruptures, and releases its two sperm cells into this cell. Structural and genetic studies indicate that the synergid cells produce an attractant that guides growth of the pollen tube to the female gametophyte and that they contain factors that control arrest of pollen tube growth and release of pollen tube contents; however, these regulatory steps are not understood at the molecular level. The proposed work focuses on analysis of the MYB98 gene that encodes a MYB transcription factor, is expressed specifically in the synergid cells, and is required for pollen tube guidance. To identify factors required for pollen tube guidance, genes acting downstream of MYB98 will be identified and analyzed. To gain insight into the synergid cell gene regulatory network, genes regulated directly by MYB98 will be identified and the regulatory sequences controlling MYB98 expression in the synergid cells will be dissected. These studies should provide new insights into the mechanisms controlling synergid cell differentiation during female gametophyte development and pollen tube guidance by the mature synergid cells. Understanding these processes may allow manipulation of the reproductive process to improve crop yield. The proposed work will provide training to undergraduate and graduate investigators and includes an outreach program to provide research experience to students from the nearby community college, as well as to minority students.
