This CAREER project will develop and strengthen a research and teaching program studying distribution and transport of nitrogen in plants. The major transport form of nitrogen in most plants is as amino acids, which are the basic building blocks for synthesis of enzymes and proteins. These metabolites are crucial for plant growth and also play a significant role for human nutrition either directly or as feed for animals. The economic and nutritional value of many crops is related to the amount and quality of proteins they accumulate, which is dependent upon transport of amino acids from sites of synthesis. However, the mechanisms regulating transport or partitioning of amino acids from sites of production in leaves or roots (source) to sites of utilization such as seeds (sinks) are not well understood. The hypothesis underlying this project is that partitioning of various amino acids between leaves and seeds is controlled by specific transporters located in the source and sink cells. Pea has been chosen as a model as it has large seeds and provides experimental access to the plasma membrane transport events responsible for amino acid import. Amino acid transporters responsible for uptake of a broad range of amino acids in pea will be analyzed with respect to their cellular localization and function. Transport processes will be manipulated by overexpressing the transporters in source and sink organs followed by analysis of effects on amino acid translocation to seeds and on nitrogen composition. The genetically-modified pea plants will provide excellent tools to explore questions about the regulation of partitioning of amino acids, and how transport of specific amino acids can affect growth and seed composition. The information gained can potentially be transferred to other crops to ensure plant productivity and enhance nutritional quality of seeds or other plant organs used as food.
Broader Impact This CAREER project will generate important new data on the fundamental processes of amino acid allocation to sink organs (e.g. seeds), and will provide the platform for future strategies aimed at manipulating amino acid and protein quality and quantity in crop plants. It will also strongly promote teaching and training of students in plant biology at all educational levels through incorporation of the research techniques and results into undergraduate and graduate level courses taught by the principal investigator (PI). These courses will provide cutting-edge research and technology information to the students. A summer course stipend will be offered to four top undergraduate students who have previously taken the PI's Plant Physiology course for work on specific parts of the project to gain first hand experience in plant molecular physiology. A graduate and postgraduate student will be involved in undergraduate tutoring and research. The project will promote effective integration of plant biology education and research at all levels and advance the PI's professional development and her contribution to the department and to student training in plant science.
