Abstract
Athyrium yokoscense (At) is a metal hyper-tolerator/accumulator fern indigenously grown in Japan and eastern Asia. Here, cadmium accumulation in the fern was kinetically analyzed using the positron-emitting tracer imaging system (PETIS). Results showed a clear difference in Cd accumulation kinesis between At and some major crops (e.g. rice and tobacco). That is, major crops slowly absorbed Cd in roots and then comparatively quickly dispersed it among whole plant body, whereas At absorbed Cd in roots within surprisingly short time, and kept the most parts in rootstock at least during the observation period. At that time, the Cd absorption rate into roots (mol h-1 plant-1) was linearly dependent on the Cd concentration in the medium (0.1-100 μM) for At. Interestingly, concentrations of some potentially competitive metals in the media (e.g. Fe, Cu, and Zn) did not influence the Cd absorption rate in At. These results would relate the mechanism of Cd hyper-tolerance and/or Cd hyper-accumulation of At.
