Pathways of cadmium fluxes in the root of the halophyte Suaeda salsa

Halophyte plants offer a greater potential for phytoremediation research for reducing the levels of toxic metals from saline soils than salt sensitive plants. Using the scanning ion-selective electrode technique, we analyzed the pattern and rate of Cd2+ fluxes at different regions of the root apex of Suaeda salsa. The Cd2+ influx in the rhizosphere was greatest near the root tip (within 150 mu m of the tip). The results indicated that Cd2+ influx into roots was significantly suppressed by the pre-treatment or in the presence of two kinds of Ca2+ channel blockers; LaCl3 and verapamil. The Cd2+ influx was also reduced by N-ethylmaleimide, a thiol blocker. Cd content determination and labeling of Cd using fluorescent dye support our conclusion. The results of this study provide a more stable theoretical basis for the phytoremediation of Cd contamination in saline soils of coastal zones. (C) 2011 Elsevier Inc. All rights reserved.