Metal tolerance caused by heterologous expression of TgSATm in A. thaliana. Independent homozygous T4 lines transformed with TgSAT-m [S 4–9 (black), S 3-1 (grey) and S 5-4 (white)], representing high, intermediate and low expressers or empty vector E 1–5 (striped). Seedlings in each ring around a central filter paper disc soaked with 100 μL of 100 mM Ni (NO3)2, 100 mM Co (NO3)2, 400 mM Zn (NO3)2 and 50 mM Cd (NO3)2, were scored for upright cotyledons (A), development of secondary leaves (B) or the development of a root hook (C). Seedlings were germinated and grown for 13 days on the assay plates before being scored. Data represent the mean of three replicate assay plates per line ± SD.