Figure 3

Regulation of Fe deficiency responses in rice roots. Ovals indicate regulatory proteins. Boxes indicate proteins responsible for Fe uptake and translocation. All depicted proteins except IDEF1, IDEF2, and OsHORZ1 are transcriptionally induced in response to Fe deficiency. Broken lines indicate putative pathways. Line colors indicate the type of regulation: black lines, transcriptional regulation; pink lines, IDEF1 protein degradation and its inhibition; red lines, unknown mechanism of regulation occurring primarily under Fe sufficiency, which may involve protein ubiquitination by OsHRZs; blue lines, putative Fe sensing by IDEF1 and OsHRZs via direct binding of Fe and other metals; green line, putative Fe sensing by IDEF2 through an unknown mechanism.