Role of Sulfur in Cadmium Accumulation of Tagetes erecta L.

The role of sulfur in cadmium (Cd) accumulation was investigated in Tagetes erecta L. Shoot Cd concentrations were significantly increased with increasing of sulfur levels in the culture solution. In another experiment, leaf application of sodium sulfate (Na2SO4) or cysteine to sulfur (S)-starved plants significantly increased Cd accumulation in shoots up to three folds or twice that of those S-starved plants. When plants were cultured at 35C, shoot Cd accumulation was significantly lower than in those cultured at 25C, however, leaf application of glutathione or cysteine significantly increased Cd accumulations in shoots than that of no application. It is suggested that elevated temperature (35C) might disturb sulfur assimilation, for example, cysteine and glutathione synthesis, thus reducing Cd accumulation. This phenomenon can be alleviated by adding thiol-containing compounds, such as cysteine and glutathione, but not by adding Na2SO4. These results indicate that thiol-containing compounds play an important role in Cd accumulation of T. erecta.