At 1000ppm Au in the solution, Au uptake was 124mgAu g−1 dry weight after 24 h of exposure, 129mgAu g−1 dry weight after 48 h reducing to 93mgAu g−1 dry weight after 72 h of exposure.Cells, when starved of a metabolite, show increased influx of that metabolite. This can explain the initial high uptake of Au in both MS and BJ. Once the cells are saturated, the uptake is dependent on the external concentration and availability of free ion exchange sites at the root surface. The initial rapid uptake may be because of diffusion, metal homeostasis or an ion exchange mechanism [6] and is indicative of the fact that BJ had reached its threshold level after 48 h exposure time