Functional Identification Of Iron-deficient Related Gene Fdr3 In Malze Roots

The expression of FDR3 (iron梔eficient related clone) was enhanced in maize roots under iron梔eficient conditions. At first the positive clone of FDR3 cDNA was screened from cDNA expression library of maize roots . The FDR3 cDNA was 3. 3 Kb in: length ,including a subclone of 2.5Kb which contains a putative ORF of 1068bp.FDR3 was inserted into the yeast expression vector pDBLeu and then was transferred to the yeast strain M3(ctrl mutant) mediated by PEG/LiAc and by electroporation . In the medium without copper and iron, onlywith ferric citrate , the expression of FDR3 could complement the growth defect of ctrl mutant .CTR1 is a member of high梐ffinity iron transport system . Total RNA was extracted from Fe梔eficient wheat roots. Northern blot analyses were carried out using32P條abeled FDR3 DNA probe which is the size of 2.5Kb. Northern blot analysis indicated that FDR3 was at higher level of transcription under iron?deficient conditions than under iron梥ufficient conditions( on day 9 and 11). Based on the analysis of hydrophobicity and transmembrane domain of its amino acid sequence ,Fdr3p has three putative transmembrane domains. We suppose that FDR3 encodes a member of membrane梑ound proteins for iron uptake and transport system.