Figure 7.

CCH mRNA was down-regulated in response to copper treatment. A, The fifth and sixth leaves were removed from Arabidopsis plants (ecotype Ler) at 16 DAG. Leaves were incubated in light for 18 h with gentle shaking in either Murashige and Skoog medium (−) or Murashige and Skoog medium plus 50 μm CuSO₄ (+). Total mRNA was extracted from leaves and used for RNA-blot analysis. Blots were probed with either 18S rRNA (control for equal loading on RNA blot), CCH, or MT1 cDNA. B, Arabidopsis plants (ecotype Col) were removed from soil and their roots submerged in 1 mm CuSO₄. Kinetics of copper uptake to the aboveground parts of the plant were measured by atomic absorption at various time points. C, Total RNA was isolated from plants after the treatment described above, as well as from plants treated in parallel with water. RNA blots made from these samples were probed with [³²P]ATP-labeled CCH (see inset). The graph plots the change in CCH mRNA levels (expressed in cpm on the RNA blot probed with the CCH probe) over time of treatment. The 0-h time point was set to 100% and subsequent values were normalized to the 0-h value.