Deoxymugineic Acid synthase: a gene important for fe-acquisition and homeostasis

Plants can be classified in two groups based on Iron (Fe) acquiring strategy. Graminaceous plants (Strategy II) acquire iron through mugineic acid family phytosiderophores (MAs). All MAs are synthesized from L-Met, sharing the same pathway from L-Met to 2'-deoxymugineic acid (DMA) and the subsequent steps may differ depending on plant specie and cultivar. DMA is synthesized through the reduction of a 3''-keto intermediate by deoxymugineic acid synthase (DMAS). Previously, all the genes involved in the synthesis of DMA have been cloned with the exception of DMAS. Recently we have reported the isolation of DMAS genes from rice, wheat, maize and barley. The DMAS belongs to aldo-keto reductase superfamily (AKR). The expression of each of the above DMAS genes is upregulated under Fe-deficient conditions in root tissue, and that of OsDMAS1 and TaDMAS1 are upregulated in shoot tissue. It seems that the expression of DMAS is not regulated at posttranscriptional level. Analysis of OsDMAS1 promoter-GUS transgenic rice suggested that DMA may have role in Fe homeostasis in rice. The cloning of DMAS genes is an important step to develop transgenic rice with increased biosynthesis and section of DMA and ultimately resistant to Fe-deficiency in calcareous soils.