Distinct uptake of tellurate from selenate in a selenium accumulator, Indian mustard (Brassica juncea)

Tellurium (Te) is widely used in industry because of its unique chemical and physical properties, and has recently become a part of everyday life as a component of phase-change optical magnetic disks. However, the recovery of Te from the environment has not been discussed yet. In this regard, we evaluated the potential use of Indian mustard (Brassica juncea), a selenium (Se) accumulator, for the phytoremediation of Te. The Indian mustard plant was exposed to selenate and tellurate and the concentrations of Se and Te and the chemical species in the plant were determined. The Indian mustard plant accumulated less Te than Se, and the amount of Te accumulated in the plant was approximately 1/69 of that of Se. Although the incorporation of selenate was reduced by increasing sulfate concentration in the medium, the incorporation of Te was not affected by it, suggesting that this plant was able to discriminate tellurate from selenate in the roots. Three Te species were detected in the plant. The major species was tellurate. The other two species were not identical to available Te standards and thus could not be identified. Consequently, the Indian mustard plant is inappropriate for the phytoremediation of Te because it can strictly distinguish tellurate from selenate.