The creation of the heavy metals tolerant plants an the trial of the phytoremediation.

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We are trying to improve heavy-metal tolerance plants by introducing genes involved in heavy-metal tolerance to plants with high biomass. In this study, we overexpressed the yeast CUP1 gene to increase metallothionein synthesis in sunflower (Helianthus annuus) and Indian mustard (Brassica juncea) call, tried to evaluate heavy-metal tolerance at the stage of callus by TTC-reducing activity, and to select tolerant clones. The transgenic calli of several strains showed high TTC-reducing activity even after a treatment with Cd for 10 days. In the transgenic calli of a few strains, which showed low TTc-reducing activity, the quantity of metallothionein was lower than that in the other transgenic strains. These results suggest that the transformation of sunflower with the CUP1 gene increased the ability to synthesize metallothioneins and made the calli tolerant to Cd. These findings also showed that the measurement of cell viability by TTC reduction is a useful method for the evaluation of C … More d tolerance at the stage of callus.On the other hand, many seedlings of the transgenic Indian mustard clone were produced, and treated with 50-400 μM Cd for 30 days in liquid culture along with the non-transformed Indian mustard. While non-transformed lndian mustard totally died several days when treated with a high Cd concentration of 45ppm, transgenic Indian mustard survived for as long as 30 days when the Cd content of its above-ground parts reached about 3,OOOppm. When we cultivated this transgenic Indian mustard in Cd-containing sandy soil, and Andosol, we found that the plant's internal Cd concentration increased to about 5OOppm or 2.3 times as high as that of non-transformed Indian mustard, which indicate that the transgenic plant can be used for Phytoremediation.In the future, we will conduct the safety tests of the transgenic plant to put it to practical use. We also think that we will need to get the public acceptance of use of transgenic plants like this for environmental decontamination purposes. Less