PI: David Mendoza-Cozatl, Univ. of Missouri, Columbia.
Co-PIs: Scott Peck, Univ. of Missouri, Columbia; Dmitri Nusinow, Danforth Plant Science Center
Iron is an essential nutrient for humans, and plants are the main dietary source of iron not only for humans but also for livestock. Iron deficiency in humans has been described by the World Health Organization as the most common nutritional deficiency affecting nearly 2.2 billion people (~30% of the world's population). Therefore, understanding how plants sense, take up and re-distribute iron in edible tissues is essential. Traditionally, iron sensing by plants was believed to occur exclusively by roots that are in close contact with iron sources in the soil, however, provocative preliminary data from our laboratories and others suggests that plants rapidly sense changes in iron concentrations in specialized cells located in leaves, termed companion cells. This project will focus on the early events of iron deficiency responses in plants and on the communication between leaves and roots to adapt when iron becomes scarce. In addition, this project will provide training to undergraduate and graduate students on cutting-edge molecular biology techniques, particularly techniques that address changes in specific tissues such as the veins of plants, which have been shown to play an important role in leaf-to-root communication. Moreover, this project will emphasize collaborative work between students from different disciplines including computer sciences, biochemistry and plant sciences. Learning how to communicate across disciplines is critical for developing novel techniques and instrumentation to study in detail how plants respond and adapt to changes in nutrient availability. In the long-term, students capable of understanding and bridging different disciplines will be well-equipped for the current competitive job market in academia and industry.
The long-term goal of this project is the identification of molecular mechanisms mediating iron (Fe) sensing and homeostasis in plants. Respiration and photosynthesis heavily depend on the redox properties of iron to generate and store energy; however, this reactivity makes iron extremely toxic at high concentrations. Therefore, plants need to sense the levels of Fe within tissues and regulate Fe uptake to prevent overload and cellular damage. Despite significant advances in identifying molecular components of the Fe deficiency response in plants, the sensing and precise location of Fe sensing in plants remains unknown. More recently, it has been found that specific cells within the leaf vasculature (companion cells) are capable of sensing changes in iron availability more rapidly than roots. This project will use a cross-disciplinary approach to address the long-standing question about the spatial (where) and temporal (when) responses to iron deficiency in plants by identifying and integrating transcriptional and protein networks at cell-specific resolution. Several techniques, such as proximity labeling, have been specifically adapted to plants to pursue proteomic studies in specific tissues. Cell-specific translatome analyses during early stages of iron deficiency will be used to define the primary (early) and secondary (responses) to iron limitation in the vasculature and will guide high-throughput protein-DNA binding experiments to identify the molecular mechanisms driving early responses to Fe deficiency in companion cells. Experimental approaches will be complemented with modeling and simulation to produce an integrated view of plant responses to changes in iron availability.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
