Quantitative RT-PCR analysis of IDEF1 (A) and its typical target genes OsIRO2, OsYSL2, OsNAS2 and OsYSL15 (B) under Fe-rich conditions in hydroponic culture. I2pro-IDEF1 transformants (line 13, T3) or IDEF1-RNAi transformants (line 2, T3; line 5, T2) were individually cultured with non-transformants (NT) and supplied with 15·8 mg L−1 Tetsuriki-TypeX fertilizer for 24 h. Transcript abundances in the roots were quantified and are expressed as ratios relative to NT levels (mean ± s.d.; n = 3–6). Significant differences from NT, analysed using a t-test (*P < 0·05; **P < 0·01), are shown.