Transcription factor involved in positive regulation of genes involved in strategy II iron acquisition, including genes for mugineic acid (MA) family phytosiderophores biosynthesis, and genes involved in S-adenosylmethionine cycle and iron transport (PubMed:31574173). May play a role in the regulation of iron deficiency response by promoting the nuclear localization of IRO2 (PubMed:31574173). Possesses transactivation activity in yeast (PubMed:31574173). Forms homodimers (PubMed:31574173). Interacts with IRO2 in the nucleus (PubMed:31574173). Expressed in the meristematic zone of lateral and primary roots. Strongly induced by iron deficiency in roots, but not in shoots. No visible phenotype under normal growth conditions, but mutant plants exhibit impaired growth, leaf chlorosis and reduced iron concentration in shoots, when grown under iron deficiency conditions. Belongs to the bHLH protein family.