Abstract
We have reported the characterization of Ni-tolerant tobacco BY-2 cell line, NIT cells. Our previous study showed that the Ni tolerance of the NIT cells was highly related to the contents of organic acids and histidine (His), and vacuolar compartmentalization of Ni. Based on these findings, subcellular distribution of Ni and these metabolites was investigated by using protoplasts and intact vacuoles derived from the NIT cells. Studies on the intracellular localization of the Ni, organic acids and amino acids revealed that all of the Ni and citrate and approximately 60% of His were localized in the vacuole. This result indicates that Ni was possibly transported into the vacuoles in the form of chelate complex. Therefore, the vacuolar transport of Ni2+, Ni-citrate or Ni-His was investigated by measuring the fluorescence of cell-impermeable Newport green DCF, Zn/Ni specific indicator, in the tonoplast vesicles from the NIT cells.
