Effects of nitrate supply site on selenite uptake by rice roots.

Selenite uptake by rice roots is regulated by many factors. The goal of this paper was to study the effects of the nitrate supply site on selenite uptake by rice roots. Using the excised-root experiment system, we found that, due to anion-anion interactions, nitrate can partly block the selenite uptake by rice roots by local action (a corporate supply of nitrate and selenite in the same portion). Using a split-root experiment system (whole-plant level), we found that (1) nitrate can also partly block selenite uptake by rice (roots and shoots) by local action; and that (2) under long-distance action (separate supply of nitrate and selenite in two different portions of the root), nitrate can partly facilitate selenite uptake by rice (roots and shoots), probably by regulating root glutathione content. Thus, our results suggest that nitrate can inhibit or facilitate selenite uptake by rice roots depending on the nitrate supply site.