FIGURE 3.

Fe-enriched endodermis is conserved in distinct plant orders. Seed cross sections belonging to members of various orders were stained with Perls/DAB and observed under light microscope. From panels (A–C), Gossypium arboreum. Eucalyptus elata and M. truncatula, respectively. (D) Single cotyledon of Arachis hypogaea. Fe staining appeared black in panels (A–C) and brown in panel (D). Outer brown–black cover in panels (A–C) are seed coats. These were already brown before the staining, thus the color do not reflect the stained Fe. In panel (A), longitudinal section of hypocotyl and cross section of folded cotyledons can be differentiated. Red arrow heads show Fe enrichment surrounding the provascular strands of cotyledons. (E) Branch of the taxonomic tree, for the whole tree refer to Figure 8. This branch shows species that were examined for Fe reserves in distinct orders and used as a visual aid. Note that only selected examples from panel (E) is shown through (A–D). Bar is 1 mm for panel (A) and 0.1 mm for panels (B–D). Red arrow heads point to examples of specific Fe accumulation pattern, closed rings around provasculature of cotyledons.