Fig. 1: SRF3 regulates root growth and iron homeostasis upon low iron conditions.

a Upper panel: Manhattan plot for GWA mapping of the root growth rate day 4–5 of natural accessions grown under low iron conditions. The horizontal dash dot line corresponds to a 5% false discovery rate threshold. Black box indicates the significantly associated SNP that is in proximity to SRF3 (At4g03390). Lower panel: Magnified associations in the SRF3 region with gene models. b Representative images of 5 day old seedlings of WT and srf3-3 under iron sufficient medium for 5 days (left panel) and then transferred to iron sufficient media (+Fe; upper right panel), or to low iron medium (–FeFZ 100 μM, lower right panel) and grown for 3 days. This phenotype has been observed at least 12 times. Scale bars, 1 cm. c Boxplots of late root growth response of plants grown for 3 days on different iron levels (–FeFZ 10, 50, 100 μM or Na-Fe-EDTA 300 μM) in WT and srf3-3 seedlings [two-ways student test (p < 0.05), n.s. non-significant]. d RNAseq read counts of differentially expressed iron homeostasis genes in roots of WT and srf3-3 in iron sufficient conditions. e 5 day old seedlings stained with propidium iodide (PI; red channel) expressing pIRT1::NLS-2xYPet (green channel) in WT and srf3-4 on sufficient (+Fe) or low (–Fe) iron medium and the related quantification [one-way ANOVA follows by a post hoc Tukey HSD test, letters indicate statistical differences (p < 0.05)]. Scale bars, 100 μm. f Confocal images of 5 day old seedlings stained with RhoNox-1 in WT and srf3-3 on sufficient medium (+Fe; upper panel) or low iron medium (ferrozine 50 μM, 30 min; lower panel) and related quantification [Independent two-ways student test (p < 0.05)]. Scale bars 50 μm.