Whole-plant imaging of Cd distribution using positron-emitting tracer imaging system

Suzui, Nobuo; Yin, Y.-G.; Igura, Masato*; Ishii, Satomi; Kawachi, Naoki; Ishikawa, Satoru*; Fujimaki, Shu

We have conducted noninvasive imaging of cadmium (Cd) in intact plants using a positron-emitting tracer imaging system (PETIS) and Cd for the purpose of understanding the mechanism of Cd translocation in plants. In our typical imaging experiment, Cd tracer has been fed to the root of large plants such as rice, and obtain the serial images of Cd distribution in the underground parts (roots and culture solutions) or the aerial parts (shoots or grains). However, whole-plant images of Cd distribution in both underground and aerial parts have not been obtained because the field of view (FOV) of PETIS is limited. In this study, we fed Cd to dwarf plants, and visualized Cd dynamics in a whole plant within the FOV of PETIS. As a result, the whole physiological process, i.e., uptake from culture solution, translocation from root to shoot and accumulation in shoot, were successfully visualized in the single imaging experiment. The time courses of Cd amounts demonstrated that the half amount of Cd fed to the solution was taken up by the root within 2 hours, and the two-thirds amount was accumulated in the shoot after 30 hours. These results imply the whole-plant imaging represents a reliable tool for the quantitative analysis of Cd dynamics.