Cadmium inducible Fe deficiency responses observed from macro and molecular views in tobacco plants.

Responses induced by Cd exposure were assessed in tobacco seedlings (Nicotiana tabacum L.) using macro and molecular indices. The 100 microM of Cd exposure reduced the total dry weight and chlorophyll index of the seedlings as much as the genuine Fe-deficiency. Concentration of Fe in the shoots decreased, whereas that in the roots increased by the Cd exposure, especially in the apoplasmic space. It is probable that Cd interferes mainly with the step of Fe-translocation from the roots to shoots and this sets the upper-part of the plant in a state of Fe-deficiency. The Cd exposure coordinately increased the expressions of the exogenous and the endogenous Fe-deficiency responsive genes, HvIDS2(pro)::GUS, NtFRO1 and NtIRT1 in the roots. This is the first data to demonstrate the responses of Cd-inducible Fe-deficiency at a molecular level.