Subcellular distribution and translocation of radionuclides in plants

The subcellular distribution of radionuclides in Glycine max Merr. (soybean) and Cucumis sativus L. (cucumber) and translocation of plant absorbed radionuclides with growth in soybean were studied. More than 60% of cellular incorporated Rb, Sr, Mn, Co, Nb, and Se remained in the supernatant fraction; 55% and 20% of Cr was bound to soybean and cucumber cell wall fractions, respectively; 70% or more of Be, Y, and Fe was fixed in the chloroplast fraction; and approx, 10% of Sc, Fe, V, and As were fixed in the mitochondrial fraction. Translocation of nuclides within the soybean plant at different stages of growth has been determined. Vanadium, Y, Be, Se, Nb, Sc, Cr, and Zr were predominantly accumulated in the root. Although the total percentage of plant uptake of Sc, Zr, Nb, and Cr was high, because of low mobility and translocation to shoot, their accumulation in the fruit fraction was negligible. The translocation of mobile nuclides in plants was demonstrated clearly by Rb, Zn, and Fe. Data on the nuclide fraction mobilized from vegetative parts into edible parts was used to assess the percentage of accumulated radionuclides in plants that may reach humans through beans.