Absorption, distribution and binding of cadmium and zinc in irrigated rice plants

Cadmium accumulation in crops

“…However, vacuolar storage at low levels of exposure is inconsistent with earlier results (Wagner 1979;Krotz et al 1989). Low molecular weight 109 Cd-and 35 S-labelled compound(s) observed in rice plant roots (Dabin et al 1978) could have been Cd complexed with glutathione, which would support the role for glutathione proposed by Vögeli-Lange and Wagner (1996).…”

“…In similar studies with lupin, approximately 5% of 109 Cd was desorbed (Costa and Morel 1993). The percentage of Cd recovered in the residue of root homogenates increased substantially as Cd in the nutrient solution of rice plants was increased from 4.4 × 10 -8 to 8.8 × 10 -7 M (Dabin et al 1978). Recent work with wheat seedlings exposed to 2 × 10 -8 M 109 Cd for 24 h, showed that <1% of root-bound 109 Cd could be desorbed with 1 × 10 -6 M DTPA (Buckley et al 1997).…”

“…They observed a 50% increase (not statistically significant) with 1 × 10 -8 M added Cd and a sixfold increase with 5 × 10 -8 M added Cd (Tukendorf and Rauser 1990). Rice plants exposed to 35 Scysteine or 9 × 10 -8 M 109 Cd in solution for 24 h accumulated 109 Cd and 35 S in the same low molecular weight soluble fraction of roots (Dabin et al 1978), which might have contained phytochelatins, glutathione or other sulphur compounds complexed with Cd. Using a sensitive technique for phytochelatins, Ahner et al (1995) have shown that concentrations of Cd 2+ as low as 10 -12 M induced the synthesis of phytochelatin in several species of marine phytoplankton.…”

Cadmium Distribution and Chemical Fate in Soybean Plants

“…In fact, Cd uptake studies, both with higher plants (6) and algae (11), employing Cd concentrations <1 ,iM, show absorption isotherms consistent with metabolically mediated transport. In metabolic studies, the proportion of Cd found in root residues compared with that found in metabolic compartments decreases when the concentration of Cd supplied to roots is decreased from 0.9 to 0.009 pM (9). Several studies have evaluated the chemical fate of Cd found in soluble fractions of roots and leaves (2,9,26 have shown Cd to be associated with protein having mol wt of 3,000 to 10,000 in roots (2,9,26) and 700 to 5,000 in leaves (2,26).…”

“…Several studies have evaluated the chemical fate of Cd found in soluble fractions of roots and leaves (2,9,26 have shown Cd to be associated with protein having mol wt of 3,000 to 10,000 in roots (2,9,26) and 700 to 5,000 in leaves (2,26). The soluble Cd containing fractions of rice roots was found to be high in cysteine (9), and it is suggested that sulfhydryl groups may play a role in fixation of Cd as they do in animal systems (2,9,16).…”