Model for the role of ethylene, through EIN2, on the upregulation of the Fe acquisition genes FRO2 and IRT1 in Arabidopsis. Fe deficiency causes enhanced ET production in roots. In the presence of ET, the CEND portion of the EIN2 protein is cleaved and shuttled into the nucleus where it increases the transcriptional activity of the EIN3/EIL1 TFs (see Introduction for more details). The accumulation of these latter TFs trigger ET responses, such as enhanced FIT transcription and, consequently, FRO2 and IRT1 upregulation. The transcription of FIT, FRO2 and IRT1 could also be triggered through alternate pathways, such as the “non canonical” ET-signaling route involving AHPs and ARRs or the ones involving other hormones, such as auxin (dashed lines). In addition to FIT, the different routes could also upregulate FRO2 and IRT1 through other TFs, such as ERF1. Abbreviations: AHPs, Arabidopsis Histidine-containing Phosphotransmitters; ARRs, Arabidopsis Response Regulators; ER, Endoplasmic Reticulum; ERF1, Ethylene Response Factor1; ET, Ethylene; NM, Nuclear Membrane; TFs, Transcription Factors. Based on [7,17,32,33,34,35,36,44,45].