We show that a basic helix-loop-helix (bHLH) transcription factor Upstream Regulator of IRT1 (URI) acts as an essential part of the iron deficiency signaling pathway in <i>Arabidopsis thaliana</i> The <i>uri</i> mutant is defective in inducing Iron-Regulated Transporter1 (IRT1) and Ferric Reduction Oxidase2 (FRO2) and their transcriptional regulators FER-like iron deficiency-induced transcription factor (FIT) and bHLH38/39/100/101 in response to iron deficiency.
In this study, the levels of the ethylene response factor AtERF72 increased in leaves and roots induced under the iron deficient conditions. erf72 mutant plants showed increased growth compared to wild type (WT) when grown in iron deficient medium for 5 d. erf72 mutants had increased root H<sup>+</sup> velocity and the ferric reductase activity, and increase in the expression of the iron deficiency response genes iron-regulated transporter 1 (IRT1) and H<sup>+</sup>-ATPase (HA2) levels in iron deficient conditions.