Fig. 1.

Induction of iron uptake mechanisms in Arabidopsis lines overaccumulating NA. Wild-type plants (Columbia ecotype Col-0, black bars) and plants with a 4-fold (K8, grey bars) or a 100-fold (K1, white bars) increase in their NA content were sown on half-strength MS medium and after 5 d transferred to an iron-sufficient medium [50 μM Fe(III)-EDTA] for 12 d. Real-time RT-PCR determination of the relative transcript levels corresponding to the genes involved in the iron uptake, AtIRT1 and AtFRO2 (A), or in the transcriptional regulation of the iron starvation response, AtFIT1 (bHLH29), bHLH38, and bHLH39 (B). Error bars represent the SE of four repetitions. IRT1 protein accumulation in roots (C) was detected using an IRT1 affinity-purified peptide antibody (upper panel). The Coomassie staining shows equal loading (lower panel). Root Fe(III) chelate reductase activity (D) was performed on a mix of five plantlets. Error bars represent the SE of four repetitions.