Supplemental Figure S1. Coleorhiza anatomy.

(A, B) Longitudinal median section of dry barley embryos from D (A) and AR (B)

grains showing coleorhiza enclosing the largest embryonic root. D and AR

embryos were indistinguishable. (C, D) Longitudinal median sections of barley

embryos 24 h after start of hydration from D (C) and AR (D) grains. (E, F) Higher

magnification of longitudinal sections of coleorhiza cells in dry barley embryos

from D (E) and AR (F) grains showing no difference in morphology or structure.

(G, H) Higher magnification of longitudinal sections of coleorhiza cells in barley

embryos after 24 h hydration from D (G) and AR (H) grains, showing some radial

expansion in D coleorhiza but more expansion as well as considerable elongation

and vacuolation in AR coleorhiza cells. (I, J) Transverse sections of coleorhiza and

enclosed roots in AR barley embryos before (I) and after (J) 24 h hydration

showing increased separation of coleorhiza cells from epidermis to root surface.

After hydration root cells were densely cytoplasmic but coleorhiza cells were

highly vacuolate. col = coleorhiza. (K, L) Longitudinal sections of cells at the tip

of the coleorhiza in AR barley seeds before (K) and after (L) 24 h hydration

showing near-isodiametric cell shape and isodiametric expansion of cells and

intercellular spaces.

Methods

(A-H, K, L) LR White sections were stained with PAS and counterstained with

0.5% fast green FCF in 95% ethanol, followed by 0.05% toluidine blue in

1% borax pH 4.4.

(I, J) Grains were fixed in 3% glutaraldehyde in 25 mM NaPO4 buffer, pH 6.8 for 2

hours at room temperature, then processed as above. Sections were stained with

0.1% toluidine blue in 1% borax, pH 4.4.

Supplemental Figure S1