Possible involvement of Ids3 in the hydroxylation of deoxymugineic acid to mugineic acid in Fe-deficient barley roots

The genomic nucleotide sequence of Ids3 (Iron deficiency specific clone no. 3) was determined. It showed high similarity to plant and fungal 2-oxoglutarate dependent dioxygenases. From northern hybridization and western blotting, IDS3 was found to be induced after 3 days of Fe-deficiency treatment and disappeared 4 days after Fe-resupply in barley roots. IDS3 was detected in roots of Fe-deficient barley and rye, but not in wheat, rice, maize, sorghum, oat, tobacco or tomato plants. This gene was found to be encoded in barley on chromosome no. 4 using ‘wheat-barley addition lines’. These findings strongly suggest that IDS3 catalyzes the hydroxylation step from deoxymugineic acid (DMA) to mugineic acid (MA).