Fe staining and root growth assay. Perls/DAB Fe staining on 4-days-old seedlings that were transferred from + Pi to + Pi or –Pi medium for 20 h. Upper panels show mature root segments of wild-type, pdr2 and lpr1lpr2 seedlings, lower panels depict the root meristem and EZ, which shows early differentiation of root hairs under-Pi. Scale bar, 200 μm. (PDF 45 kb)