Fig. 4

Cell wall thickness and immunogold localization of wall carbohydrate epitopes. a The mean and median values of PT cell wall thickness are shown by the dash-lines and the line in the middle of the box, respectively. The mean cell wall thickness is similar between ChF (160 nm, n = 100), PF (156 nm, n = 50), and HPF (164 nm, n = 100) sections. b Immunogold labelling (examples indicated by arrowheads) for callose (top panel), LM6 against (1–5)-α-L-arabinosyl residues of rhamnogalacturonan-I (RG-I, middle panel), and LM15 against the xyloglucan motif, (XXXG, bottom panel) of ChF/LR white and/or ChF/Epon sections. The labelling for callose localizes to the inner cell wall layer and serves as reference to distiguish the primary from the secondary cell wall. While the antigenicity is more highly preserved in ChF/LR white sections than ChF/Epon sections (as revealed by the relative higher abundance of the gold particles), there is considerably high shrinkage of the plasma membrane on LR white sections. The distributions of RG-I and xyloglucan occur in both the inner and outer cell wall layers. Scale bar = 500 nm