Expression profiling of the Arabidopsis ferric chelate reductase (FRO) gene family reveals differential regulation by iron and copper.
The Arabidopsis FRO2 gene encodes the iron deficiency-inducible ferric chelate reductase responsible for reduction of iron at the root surface; subsequent transport of iron across the plasma membrane is carried out by a ferrous iron transporter (IRT1). Genome annotation has identified seven additional FRO family members in the Arabidopsis genome. We used real-time RT-PCR to examine the expression of each FRO gene in different tissues and in response to iron and copper limitation. FRO2 and FRO5 are primarily expressed in roots while FRO8 is primarily expressed in shoots. FRO6 and FRO7 show high expression in all the green parts of the plant. FRO3 is expressed at high levels in roots and shoots, and expression of FRO3 is elevated in roots and shoots of iron-deficient plants. Interestingly, when plants are Cu-limited, the expression of FRO6 in shoot tissues is reduced. Expression of FRO3 is induced in roots and shoots by Cu-limitation. While it is known that FRO2 is expressed at high levels in the outer layers of iron-deficient roots, histochemical staining of FRO3-GUS plants revealed that FRO3 is predominantly expressed in the vascular cylinder of roots. Together our results suggest that FRO family members function in metal ion homeostasis in a variety of locations in the plant.
Mukherjee
Indrani
I
Department of Biological Sciences, Coker Life Sciences, University of South Carolina, 700 Sumter St, Columbia, SC 29208, USA.
Campbell
Nathan H
NH
Ash
Joshua S
JS
Connolly
Erin L
EL
D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D003300:Copper / Q000494:pharmacology*; D038181:FMN Reductase / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D007501:Iron / Q000494:pharmacology*; D005810:Multigene Family; D010802:Phylogeny; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis
D029681:Arabidopsis Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D003300:Copper; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase