A Kinetic analysis of cadmium accumulation in a Cd hyper-accumulator fern, and tobacco plants

Yoshihara, Toshihiro*; Suzui, Nobuo; Ishii, Satomi; Kitazaki, Mayu*; Yamazaki, Haruaki*; Kitazaki, Kazuyoshi*; Kawachi, Naoki; Yin, Y.-G.; Tanabata, Sayuri*; Hashida, Shinnosuke*; Shoji, Kazuhiro*; Shimada, Hiroaki*; Goto, Fumiyuki*; Fujimaki, Shu

Cadmium (Cd) accumulations in a Cd hyper-accumulator fern, (), and tobacco, (), were kinetically analysed using the positron-emitting tracer imaging system under two medium conditions (basal and no-nutrient). In , maximumly 50% and 15% of the total Cd accumulated in the distal roots and the shoots under the basal condition, respectively. Interestingly, a portion of the Cd in the distal roots returned to the medium. In comparison with , a little fewer Cd accumulations in the distal roots and clearly higher Cd migration to the shoots were observed in under the basal condition (maximumly 40% and 70% of the total Cd, respectively). The no-nutrient condition down-regulated the Cd migration in both species, although the regulation was highly stricter in than in (almost no migration in and around 20% migration in ). In addition, the present work enabled to estimate physical and physiological Cd accumulation capacities in the distal roots, and demonstrated condition-dependent changes especially in . These results clearly suggested occurrences of species-/condition-specific regulations in each observed parts. It is probable that integration of these properties govern the specific Cd tolerance/accumulation in and .