Plants have developed two distinct mechanisms, i.e., strategy I (reduction strategy) and II (chelation strategy), to mobilize insoluble Fe(III) in the rhizosphere and transport it through the plasma membrane. Arabidopsis thaliana and other dicots rely on strategy I. In this strategy, the rhizosphere is first acidified by a PM-localized H+-ATPase, AHA2. Then, FERRIC CHELATE REDUCTASE 2 (FRO2) reduces Fe(III) to soluble Fe(II). Finally, the reduced Fe is taken up by a high-affinity transporter, IRON-REGULATED TRANSPORTER 1 (IRT1). Root ferric chelate reductase activity can be quantified spectrophotometrically by the formation of Purple-colored Fe(II)-ferrozine complex in darkness.

Arabidopsis thaliana (拟南芥)

Ferric chelate reductase (铁螯合物还原酶)

FRO (FRO)

Enzyme activity (酶活)

Root (根)