A new visualization technique for the study of the accumulation of photoassimilates in wheat grains using [(11)C]CO(2).

Non-invasive real-time visualization of the accumulation of photoassimilates in the grains of an ear of wheat using [(11)C]CO(2) and positron emitting tracer imaging system (PETIS) was studied. [(11)C]CO(2) was supplied to the center of a fully expanded leaf of a wheat plant for an initial 10 min, and the transportation of (11)C-labeled photoassimilates into the grains of the ear was monitored for 120 min using the PETIS. Each grain was clearly identified in the obtained animation. The (11)C-labeled photoassimilates arrived at the ear from the [(11)C]CO(2)-absorbing leaf within 53 min from the time of supplying [(11)C]CO(2). After that, grains appeared on the image one by one from the basal part and full images of the grains appeared within 20 min. The time course of the accumulation of photoassimilates into each grain showed a different profile. Furthermore, the PETIS data suggested that the photo-condition of the ear plays an important role in the transportation of photoassimilates in wheat. PETIS can be used to visualize the dynamics of the substances in a living plant in real time and can exhibit the time course analysis of substances, such as the transportation, distribution, and accumulation.