Radiographic Imaging of Zinc and Iron Uptake

After ⁶⁵Zn administration, plants were harvested and roots were blotted dry and laid out on an absorbent pad for imaging. Shoots were also laid out on a separate absorbent pad for imaging. Radiographic images of different tissue areas (roots and shoots) were acquired by exposing phosphor plate films. Phosphor plates of roots were exposed for 36 h while plates of shoots were exposed for 120 h to acquire a sufficient signal. After exposure, phosphor plates were then read using the Typhoon 9000 imager (Typhoon^TM FLA 9000, GE Healthcare, Piscataway, NJ, USA). Images were only used qualitatively for determining spatial patterning of ⁶⁵Zn tracer in roots and shoots; hence no attempt was made to normalize image data. Comparative whole-plant radiographic images of ⁵⁹Fe³⁺ and ⁵⁹Fe²⁺ were also acquired from our prior work [16 (link)], but because of the faster decay rate of this radionuclide (t_½ 44.5 day), we only needed to expose these tissues for 16 h.