Fig. 3: Fe-dependent inhibition of primary root growth in NH4+ medium.
From: Phloem iron remodels root development in response to ammonium as the major nitrogen source
a Primary root elongation of Col-0 seedlings in NO3−-N or NH4+-N source with various doses of Fe. Center line represents mean and bounds of box are SD; whiskers indicate the minimum and maximum values; n = number of seedlings. P values <0.05 indicate significant interactions between N form and Fe dose (two-way ANOVA with post-hoc Tukey HSD test). b NH4+-sensitivity comparison of Col-0, isas, lpr2-1, and complementation line COM#7 in Fesuff (100 µM) and Felow (10 µM) conditions. c Fe deposition indicated by Perls/DAB staining in primary roots. d Close-up view of Fe deposition in root stele of Col-0 seedlings grown in Fesuff NH4+ medium. Ep epidermis, Co cortex, En endodermis, Pe pericycle, Ph phloem, Xy xylem. e Perls/DAB staining in the phloem of the primary roots of Col-0 seedlings grown in Fesuff NH4+ medium. Red and green arrows show Fe depositions at lateral cell walls and sieve plates of the phloem, respectively. f Acetone washed-Perls/DAB staining in phloem of the primary roots of Col-0 seedlings grown in Fesuff NH4+ medium. The Perls/DAB-stained roots were washed with acetone for 3 h. Four-day-old seedlings of the indicated genotypes were transferred to NO3− or NH4+ medium with various doses of Fe supply and analyzed 4 days after seedling transfer. Each experiment was repeated independently three times with similar results, and a representative experiment is shown.
