Fig. 4

Root growth in fer and irt1 mutant plants and phenotypes of frd3 roots. a 4-days-old seedlings were transferred from + Pi to + Pi or –Pi medium for up to 6 days. Daily increase in root growth was measured and illustrated in segmented boxes within the bar graph (±SE, n ≥ 15). Standard error was calculated from the average total root growth. b Total increase in root length after transfer from + Pi to either + Pi or –Pi medium t-test; p < 0.05 (±SE, n ≥ 20). c, d, and e Fe staining and root growth assays of wild-type and frd3-7 seedlings. 4-days-old plants were transferred from + Pi to + Pi or –Pi medium for up to 6 days. c Perls staining in different root segments 20 h after transfer to + Pi or –Pi medium. Upper and middle panels show mature root segments. The lower panels show the RAM and early differentiation zone. Scale bar 200 μm. d Fe (Perls) and aniline blue (AB) callose staining of root tips and differentiated root segments 6 days after transfer to –Pi medium. Scale bar 100 μm. e Root growth of wild-type and frd3-7 seedlings within 6 days after transfer to Pi-depleted medium. The bar graph shows the daily increase in root growth, illustrated in segmented boxes. Standard error was calculated from the average total root growth. *** t-test; p = 1.85⁻⁸ (±SE, n ≥ 20). Overview images show the root growth after 3 days and 6 days on –Pi medium . Arrows indicate the position of the root tip, directly after transfer to –Pi (t = 0), as well as 3 days and 6 days after transfer. Scale bar 1000 μm. (See also Additional file 14: Figure S3)