Mechanisms of Transport Through Plasmodesmata

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All organisms are made up of cells, a basic unit of life. While some microorganisms, such as bacteria, are single celled, most plants and animals are multicellular, composed of many billions of cells, and tens or hundreds of different cell types. Each cell type has a specialized function, for example different cell types in plants function to take up nutrients from the soil, to photosynthesize, or to promote growth. Communication between different cell types is critical for the proper growth and viability of plants. This project will study a system for cell-to-cell communication, involving the transport of signaling molecules through special channels called plasmodesmata. Genes that control the transport process have been identified, and their role in development and physiology will be studied. For example, one such gene encodes a chaperone, a protein that can unwind other molecules, to allow them to pass through plasmodesmata. These studies will provide new insights into plant biology, that could provide strategies to improve crop plant productivity. Outreach activities will target high school students from the local community, as well as underrepresented groups, to provide them training and mentorship in science. Such training is important to maintain a strong science and technology base for the U.S. workforce.An important and unique form of cell-to-cell communication in plants occurs by the trafficking of protein and RNA based signals through plasmodesmata, specialized channels that are embedded in the cell wall. Despite their central importance to plant development, physiology and defense, the general mechanism and regulation of trafficking through plasmodesmata is poorly understood. This project will use genetic, cell biological and biophysical approaches to understand how regulatory transcription factors important for plant growth are able to traffic between cells, to transmit important developmental signals. A novel genetic screen has been developed to discover genes that are involved in cell-to-cell trafficking of these proteins. The Jackson lab has already identified two genes, a chaperonin, and a GTPase, using this approach. These discoveries suggest mechanisms by which the proteins traffic, for example by partial unfolding of the protein, or by signaling by the GTPase, to allow their transport through the plasmodesmal channel. This proposal will further investigate the mechanism by which these genes facilitate transport, and will discover new factors that control the process. Studies of the trafficking mechanisms have the potential to make significant improvements to plant productivity, by providing tools to selectively regulate trafficking of developmental regulators, to limit the spread of pathogens, or to understanding the transport of metabolites into sink tissues, which is critical for plant growth. Hence, this proposal will advance knowledge in a fundamental area of plant biology, and will bring potential improvements to US agriculture. The project will also train a number of young scientists at various levels, as well as develop resources to involve high school students in modern biology research. The Principal Investigator directs the "Partners For the Future" Program at Cold Spring Harbor Laboratory, which allows local high school students to experience life in a research lab. He will also develop an educational exchange with a high school in Queens, New York, which predominantly serves minority students. This activity brings exposure to the excitement and applications of scientific research to students who otherwise have little opportunity for contact with scientific research.