Abstract
In the previous report, we evaluated intracellular high concentration of organic acids and histidine in Ni-tolerant cell line from tobacco BY-2 suspension cultured cells (NIT cells). The mechanism of detoxification of Ni in NIT cells may involve sequestration into the vacuoles as Ni-organic acid complex. To investigate whether Ni is localized to vacuoles, we visualized Ni with the fluorescent indicator (Newport Green DCF). Fluorescence was observed in vacuole, suggesting that NIT cells accumulate Ni into the vacuole. We also compared Ni uptake between NIT cells and control cells using isolated miniprotoplasts and vacuoles. There was no difference of uptake in miniprotoplasts. In vacuoles, NIT cells had higher ability of uptake higher than control cells in presence of citrate. These results suggest that Ni uptake into the vacuoles is enhanced by organic acid chelation in NIT cells.
