Molecular imaging for plant physiology: Imaging of carbon translocation to sink organs

Radionuclide-based imaging technologies have provided exciting new opportunities to life science researchers. However, success in the field of plant science is limited because most methods for studying plants are invasive and require statistical analysis and a large number of test plants. To clarify the mechanism of the growth and development of the agricultural produces to be harvested, we performed imaging experiments of sugar translocation to the sink organ of fruit. A leaf near the target fruits (eggplant and tomato) was exposed to carbon-11-labeled carbon dioxide, and the translocations of carbon-11-labeled photoassimilate into fruits were assessed by images obtained using the positron-emitting tracer imaging system and small animal positron emission tomography system. Serial images thus obtained showed gradually increasing ¹¹C activity and its nonuniform distribution in the fruit. These experimental methods will be useful in not only investigating plant physiology, such as mechanisms underlying fruit growth, but also solving certain environmental and food problems.