The evaluation of cadmium, zinc and nickel accumulation ability of transgenic tobacco bearing different transgenes

Tobacco, Nicotiana tabacum L., var. Wisconsin 38 as the control (WSC), and four genetically modified lines of the same variety, were tested for Cd, Zn and Ni accumulation. Genetically modified lines of the same variety, bearing the transgene CUP1 (gene coding a yeast metallothionein), GUS (reporter gene for ß-glucuronidase), HisCUP (CUP combined with a polyhistidine tail), and HisGUS (reporter gene for ß-glucuronidase, combined with a polyhistidine tail) under a constitutive promoter, enabling it to follow the heavy metal tolerance and uptake changes as a function of the transgene present. Control and transgenic lines were tested for accumulation of risk elements on sand nutrient medium with the addition of cadmium, zinc and nickel. The results showed high Cd accumulation ability of HisCUP line. The Cd content in aboveground biomass was increased by 90% compared to the non-transformed control and Cd content in roots was decreased by 49%. Determination of Zn content in aboveground biomass did not confirm higher uptake by transgenic plants significant for phytoremediation. The Ni content was significantly increased in aboveground biomass of HisGUS construct. GUS construct introduced the ability to accumulate all investigated metals; the others accumulated only one in extended amount.