Fe-deficiency tolerance, root Fe content, and IRT1 expression in M. xiaojinensis and M. baccata. A, Fe-deficiency symptoms in M. xiaojinensis and M. baccata grown under Fe-deficient conditions and short tandem repeats analysis of the IRT1 promoter. The peak at 716 corresponds to the FUE promoter sequence with the TATA-box, and the peak at 727 corresponds to the FUI promoter sequence without the TATA-box. B, Root Fe content in M. xiaojinensis and M. baccata supplied with 0 μm Fe2+ or 40 μm Fe2+ for 0, 3, and 6 d. C, Relative expression of IRT1 in M. xiaojinensis and M. baccata supplied with 0 μm Fe2+ or 40 μm Fe2+ for 0, 3, and 6 d. D. Variations in the IRT1 promoter fragment between the FUE and FUI alleles. (See full sequences in Supplemental Fig. S1.)