This award is for the development of short-lived radioisotope tracing instrumentation in order to track in real time the assimilation, translocation, and export of materials within and between living plants under controlled environmental conditions. The Radioisotope Tracing with Environmental Controls (RTEC) system is based on the use of short-lived radioisotopes and gamma-ray coincidence counting techniques. Coincidence counting is an efficient and economical method of tracing the accumulation of radioactively tagged compounds in applications where high spatial resolution is not required. The implementation of the system will utilize the plant growth facility and the nuclear laboratory at the university, which are less than 100 meters apart. This RTEC system will be used to improve the mechanistic understanding of plant physiological responses to environmental change. Nine research groups are currently involved in the collaboration. The proposed instrument will provide the capabilities for examining dynamic effects of environmental change on carbon (C) and nitrogen (N) allocation in plants. In particular, the RTEC system will enable researchers to make some of the first systematic measurements of carbon and nitrogen translocation in different plant species at the plant-soil interface and within single plants under precisely controlled environmental conditions, information that will dramatically improve understanding of the controls on plant carbon sequestration. The research enabled by the RTEC system will complement field research projects that study the effects of elevated CO2 levels on plant growth. This instrument will enable measurements that can potentially reveal the mechanisms responsible for the apparent lack of long-term carbon sequestration by mature trees that has been observed in large-scale Free Air Carbon Dioxide Enrichment experiments that are underway globally. In addition, this instrument will open opportunities for research on topics such as the dynamics of nutrient uptake and distribution (using Nitrogen-13 tagged nutrients), water absorption and transport (using both Fluorine-18 in solution and Oxygen-15 tagged water), the carbon-nitrogen balance in plant growth (using Nitrogen-13 tagged nutrients and Carbon-11 tagged CO2), and the role of microbial activities in the carbon-nitrogen cycle.
In addition to its scientific benefits, this project will involve graduate and undergraduate students in frontier interdisciplinary research in biology and physics. For example, undergraduate biology and physics students will help with the assembly and testing of the gamma-ray detectors and will assist with the design, assembly and installation of the detector support structure in the growth chamber. Undergraduate students will also work on the design, installation and testing of the gas circulation loop used in the CO2 studies and with the overall system testing. Existing collaborations with physics faculty members at two regional historically black universities will encourage their use of this research instrumentation.
