Abstract
Expression of the Ids2 (iron deficiency-specific clone 2) gene was compared between native barley and heterogenous tobacco regarding spatial specificity and iron-deficiency responsiveness. The results of Northern blot and in situ hybridization analyses demonstrated that the Ids2 expression in barley was specific to the endodermis and/or pericycle and in the cortex of roots, and responded exactly to iron starvation. Analysis of the GUS activity regulated by eight 5’-deletion clones of the Ids2 promoter in tobacco exhibited that every clone could promote root specific and iron-deficiency responsive expression. Aspects of the spatial specificity and iron-deficiency responsiveness (e.g. sensitivity, stability and returnability) in tobacco were also similar to those in barley, although a few variations were recognized. It is probable that even the shortest Ids2 promoter region in this experiment (-272/-47) contains the iron-deficiency-inducible and the root-specific cis-element(s), which is recognized by two different types of iron-acquisition strategy plants, barley and tobacco.
