Table III.
Nickel content in leaf tissue, leaf protoplasts, and leaf vacuoles of T. goesingense and T. arvense
| Leaf Ni | Protoplast Ni | Vacuolar Ni | ||
|---|---|---|---|---|
| nmol g−1 fresh biomass | nmol per 106 protoplasts | nmol per 106 vacuoles | % total protoplast Nia | |
| T. goesingense | ||||
| 1 week of Ni exposure | 613 ± 337 | 8.6 ± 4.1 | 6.0 ± 2.4 | 74.7 ± 18.4 |
| (10 μm Ni) | ||||
| 1 d of Ni exposure | 15.6 ± 5.6 | 0.23 ± 0.05b | 0.11 ± 0.01b | 52.7 ± 8.7c |
| (1 μm Ni) | ||||
| T. arvense | ||||
| 1 d of Ni exposure | 18.6 ± 11.1 | 0.24 ± 0.17 | 0.05 ± 0.01 | 25.4 ± 12.4c |
| (1 μm Ni) | ||||
Values are means of three experiments ± sd.
Because total leaf and protoplast Ni showed considerable variability between replicate experiments and thus individual plants (see “Material and Methods”) the percentage of Ni localized in the vacuole-enriched fraction in each independent replicate experiment (n = 3) was calculated and used to derive a mean ± sd for the exposure regime or species, respectively.
Values represent mean ± sd of two independent experiments; the third experiment was not included in the mean as it represented a clear outlier (leaf, and thus protoplast and vacuolar Ni concentration were found to be unusually low; Krämer et al., 1997). However, the percentage localization of Ni between the protoplast and vacuole was similar in all three experiments and therefore all the percentage data was included in the mean and used in the t-test (see footnotes a and c).
Values significantly different (t test, P < 0.05).