3.5 Pectins and arabinogalactan proteins in the leaves ofCapparis odoratissima
Immunolocalization of pectin and arabinogalactan protein epitopes with monoclonal antibodies showed a dual topological pattern. Pectin epitopes were present in the cell walls of both adaxial and abaxial epidermis (Figure 7a-b), as roughly detected in fresh samples with ruthenium red Supplementary Figure 1a), in the external walls of the cells composing the spongy mesophyll (Figure 7c), and the external cell walls of the peltate hairs (Figure 7d; Supplementary figure 1b), but not in the idioblasts. The presence of arabinogalactan proteins was roughly detected with the beta glucosyl Yariv Reagent, which showed an intense red color in areas with idioblasts (Supplementary Figure 2). More specifically, the epitopes recognized by the JIM8 monoclonal antibody labelled a narrow area that corresponded with the lumen of the idioblasts, from their adaxial projection (Figure 7e), through the columnar lumen in the palisade parenchyma (Figure 7f), to the lumens of the anchoring areas of the peltate hairs (Figure 7g). As a result, AGPs coated the continuum of lumens between the peltate hairs and idioblasts.