99mTc Based Approaches to the Study of Plant Vascular Transport Using Scintigraphic Imaging
The biodistribution of Technetium (Tc) in plants has been widely studied and reported in the literature focussing on the incorporation of environmental 99Tc into the food chain via the soil/plant system. The principle interest in this area of research has been 99Tc as a by-product of nuclear weapons testing, nuclear weapons detonation and nuclear accidents.
In soil, technetium pertechnetate (99Tc O4-) is the most stable surface chemical form of Tc and is highly mobile in biogeochemical cycles. Tc O4- is known to be extracted by plant roots, transported by the xylem and reduced in the leaves (99Tc is not evaporated) although the mechanism of action are not entirely clear.
Measuring Tc distribution in plants has been challenging. While much has been learned, many questions remained unanswered because 99Tc, 95mTc and even 99mTc have all been previously measured following sample counting at 24 hour intervals (or longer).
The aim of this investigation was to examine the potential of 99mTc based radiopharmaceuticals in conjunction with scintigraphic imaging on a gamma camera to provide physiological imaging in grape vines. We have demonstrated for the first time that Tc accumulates in fruit: the unripe berries of the grape vine. The high temporal resolution of our experiments has allowed us to conclude that scintigrgaphic imaging of 99mTcO4- is an excellent non-destructive, minimally invasive means of studying the dynamics of plant physiological processes.