Table 1. Accumulation of Cd, Zn and Cu ions in transgenic sugar beet shoots under complex heavy metal stress.
| Amount of heavy metal accumulated by transgenic sugar beet shoots [μg mg-1 dry weight (DW)] a | |||||
|---|---|---|---|---|---|
| Transgenic lines | Ions | Cd-Zn | Cd-Cu | Zn-Cu | Cd-Zn-Cu |
| wt | Cd2+ | 25.2±2.7a | 21.9±1.5a | ND | 17.6±1.1a |
| Zn2+ | 18.7±1.6a | ND | 23.2±1.6a | 13.3±0.9a | |
| Cu2+ | ND | 20.2±1.3a | 25.9±2.0a | 15.6±1.3a | |
| s2 | Cd2+ | 135.6±9.6b | 114.2±7.1b | ND | 96.5±5.7b |
| Zn2+ | 100.5±5.9b | ND | 133.2±7.7b | 78.7±4.9b | |
| Cu2+ | ND | 93.1±5.7b | 139.8±8.9b | 80.2±4.8b | |
| s4 | Cd2+ | 100.2±6.3c | 56.6±5.4c | ND | 73.2±5.2c |
| Zn2+ | 66.3±4.2c | ND | 78.9±5.2c | 53.8±4.3c | |
| Cu2+ | ND | 52.5±3.9c | 80.3±5.3c | 60.5±4.4c | |
| s5 | Cd2+ | 56.8±4.6d | 69.8±5.1d | ND | 22.2±2.1d |
| Zn2+ | 33.9±3.3d | ND | 100.1±6.1d | 16.4±1.5a | |
| Cu2+ | ND | 41.6±3.2d | 106.9±5.8d | 16.5±1.1a | |
a Transgenic sugar beet lines overexpressing StGCS-GS (s2, s4 and s5) and wild-type sugar beets (wt) were treated with double or triple combinations of 50 μM CdCl2, ZnCl2 and CuCl2, designated as Cd-Zn, Cd-Cu, Zn-Cu and Cd-Zn-Cu. Shoots were collected for analysis of ion accumulation in triplicate. Differences in the means ± standard deviation with a 5% level of significance are indicated (a-d). ND: not detected.