Expression of a gene specific for iron deficiency (Ids3) in the roots of Hordeum vulgare.

To clone genes required for the synthesis of mugineic acid (MA) or for the transport of Fe(III)-MA, a lambda ZAPII cDNA library was constructed from poly(A)(+)-RNA isolated from Fe-deficient barley roots. The cDNA library was then used for differential screening of barley roots that had been grown in the presence and absence of iron. Seven clones that hybridized specifically to the probe for Fe deficiency were selected. One clone, presumably encoding a full-length mRNA, as deduced from Northern hybridization, was sequenced. The clone consisting of 1685 nucleotides encoded a putative protein of 169 amino acids and an M(r) of 18704. The gene was specifically expressed in the roots of iron-deficient barley. A search for homologies in a protein database (NBRF) revealed that the predicted protein product has a functional peptide domain that resembles that of 2-oxoglutarate-dependent dioxygenases.