EXPRESSION OF A GENE-SPECIFIC FOR IRON-DEFICIENCY (IDS3) IN THE ROOTSOF HORDEUM-VULGARE

To clone genes required for the synthesis of mugineic acid (MA) or for the transport of Fe(III)-MA, a lambdaZAPII cDNA library was construct ed 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 No rthern hybridization, was sequenced. The clone consisting of 1685 nucl eotides encoded a putative protein of 169 amino acids and an M(r) of 1 8704. The gene was specifically expressed in the roots of iron-deficie nt barley. A search for homologies in a protein database (NBRF) reveal ed that the predicted protein product has a functional peptide domain that resembles that of 2-oxoglutarate-dependent dioxygenases.