Abstract
Cadmium (Cd) is one of the most toxic heavy metals for all organisms, and causes serious health problems in humans. Cd accumulation in rice grains has become a major agricultural problem in Japan.
We have reported that OsNRAMP1 was localised to the plasma membrane, and OsNRAMP1 mediated Cd transport. Furthermore, the expression of OsNRAMP1 in the roots of high Cd-accumulating cultivars was higher compared with low Cd-accumulating cultivars. In this study, we investigated the role of OsNRAMP1 in Cd uptake and transport in rice using OsNRAMP1-overexpressing (35S) and -suppressing (RNAi) rice.
The growth of 35S-rice was significantly inhibited both in shoots and roots. On the other hand, the growth of RNAi-rice was not different from non-transformed rice (WT). In the presence of 1 μM Cd, the Cd concentration in the leaves of 35S-rice was significantly higher than that of WT, whereas that in the roots of 35S-rice was lower than WT. Under this condition, the Cd concentration in the leaves of RNAi-rice was lower than that of WT. The Cd concentration in the roots of RNAi-rice was same as WT. The results suggest that OsNRAMP1 is involved in Cd accumulation in rice shoots.
