Figure 2.

In situ cell wall analysis on resin sections of Brachypodium root cap. (A-C) LR White resin sections (1 μm thick) of Brachypodium root tip stained with toluidine blue. (A) Longitudinal section through the root tip with indicated root cap: RC, root meristem: RM and border cell: BC. (B) Cross-section through the root cap. Note the thickness of the cell wall increases toward the surface. (C) Close-up to the region marked by dashed square in B. The arrow depicts the diffuse intercellular material and the arrowhead the intact cell wall of a detaching cell. (D-F) Staining of the region of the root cap with a detaching layer of cells. (D) Staining with β-(1,4)-glucan-specific dye Calcofluor White (CW) and (E) COS⁴⁸⁸ probe specific for HG with low degree of esterification. (F) Overlay of the 2 channels with indicated line of signal plot profile in G and 3 regions of interest. Note the COS⁴⁸⁸ staining of the intercellular material (arrows). (G) The signal plot profile of CW and COS⁴⁸⁸ signal intensities over the dashed line in F. The numbers indicate the cell wall regions marked in F. Note there is no loss of the total amount of the signals when the cells separate (compare the total area of the peaks marked 1 and 2). Scale bars: 30 μm.