Abstract
Athyrium yokoscense (Ay) is a metal hyper-tolerator/accumulator fern indigenously grown in Japan and eastern Asia. Here, cadmium accumulation in the fern was kinetically analyzed under 1/4MS and 0.5mM CaCl2 basal medium conditions at 25 degree centigrade (C) or 4 C root temperature conditions using the positron-emitting tracer imaging system (PETIS). Results showed a clear difference in Cd accumulation kinesis between Ay and tobacco (Nt). That is, Ay absorbed fewer Cd in roots and took smaller part of them up to leaves under the Ca condition than the MS condition at 25 C. Nt also absorbed fewer Cd in roots under the Ca condition, though it took considerably larger parts of them up to leaves at 25 C. Interestingly, when the root temperature was decreased to 4 C, Ay absorbed rather greater Cd in roots under the Ca condition than under the MS condition, but did not took most parts of them up to leaves. Nt showed almost similar amount of Cd uptake into roots under both of the conditions at 4 C, whereas it took larger parts of them up to leaves under the Ca condition than the MS condition. These results would be based on a difference in the mechanism of Cd transport between Ay and Nt.
