Mechanisms of Gene Expression by the embryo MADS-factor AGL15, and roles in Glycine max Somatic Embryogenesis

The project goals are to better understand how AGLl5 functions in embryogenesis. AGLl5 is a member of the plant MADS-family that act as DNA-binding regulatory factors and often play central roles in critical developmental decisions. All evidence to date indicates a role for AGLl5 in global aspects of embryo development. We identified genes directly regulated by AGLI5, but this work raised more questions because some genes are expressed in response to AGLI5, while others are repressed. Recent work has indicated that AGLl5 may contain both activation and repression functions within its C-terminal domain. These and other regions of AGLl5 are likely to interact with protein co-regulators to determine how AGLl5 acts at different in vivo DNA-binding sites. Putative interacting proteins have been identified by yeast 2-hybrid that are involved in chromatin architecture and gene regulation, including other members of the MADS-domain family. In this proposal, we outline experiments to further characterize the C-terminal domain and the role of protein-protein interactions with the long-term research goal to better understand regulatory networks during seed development. Once interactors are verified, chromatin immunoprecipitation experiments will be performed to look for genes directly regulated by distinct AGL 15-interactor complexes. Finally, an ortholog of AGL 15 has been isolated from soybean (GmAGLI5) and preliminary experiments indicate that GmAGLl5 may act similarly to Arabidopsis AGLl5 in promoting embryogenesis. Further work to test the effectiveness of GmAGLl 5 as a tool for production of transgenic soybean plants is proposed. For many crops, seeds are the harvest commodity and a fundamental understanding of regulatory networks active during seed development will be essential to developing molecular strategies to increase agricultural productivity. Basic research on embryogenesis may impact on many aspects of seed development and quality, including, but not limited to, optimal yields and nutritional value, improved viability and vigor, as well as engineering to allow new value-added products. Therefore, the proposed work specifically addresses the USDA goal involving Improvement of the Nation's Nutrition and Health. Although many of the proposed experiments use Arabidopsis, the many tools developed for this model organism provide the most efficient means to accomplish the specific aims. Recent results with soybean indicate that knowledge gained in Arabidopsis will be transferable to important crop plants.