Under conditions of reduced iron availability, most frequent in calcareous soils, plants induce the "Fe Deficiency Response" to improve root Fe uptake. The transcription factor FIT is essential for such a response in strategy I plants, such as Arabidopsis thaliana. From microarray analysis of Arabidopsis roots, it is known that three different cytochrome P450 genes, CYP82C4, CYP82C3 and CYP71B5 are up-regulated under Fe deficiency through a FIT-dependent pathway. We show that, out of these three P450 genes, only CYP82C4 strongly correlates with genes involved in metal uptake/transport. The CYP82C4 promoter, unlike those of CYP82C3 and CYP71B5, contains several IDE1-like sequences (iron deficiency-responsive element) as well as an RY element. While confirming that the CYP82C4 transcript accumulates in Fe-deficient Arabidopsis seedlings, with circadian fluctuations in a light-dependent way, we also demonstrate that such accumulation is suppressed under Fe excess. Full suppression of CYP82C4 expression, as observed in the atc82c4-1 KO mutant, is associated with longer roots at the seedling stage. We propose that CYP82C4 is involved in the early Fe deficiency response, possibly through an IDE1-like mediated pathway.
Copyright © 2011 Elsevier GmbH. All rights reserved.