Radio-Metabolite Analysis of Carbon-11 Biochemical Partitioning to Non-Structural Carbohydrates for Integrated Metabolism and Transport Studies

existing non-invasive 11 C-based methodologies for the study of phloem transport. In this report, we present methods using 11 C-labeled CO2 to trace carbon partitioning to the major non-structural carbohydrates in leaves—sucrose, glucose, fructose and starch. High-performance thin-layer chromatography (HPTLC) was adapted to provide multisample throughput, raising the possibility of measuring different tissues of the same individual plant, or for screening multiple plants. An additional advantage of HPTLC was that phosphor plate imaging of radioactivity had a much higher sensitivity and broader range of sensitivity than radio-HPLC detection, allowing measurement of 11 C partitioning to starch, which was previously not possible. Because of the high specific activity of 11 C and high sensitivity of detection, our method may have additional applications in the study of rapid metabolic responses to environmental changes that occur on a time scale of minutes. The use of this method in tandem with other 11 C assays for transport dynamics and