Figure 8.

Ultrastructure of the Cuticle of the Stem Epidermis of Wild-Type and Cutinase-Expressing Arabidopsis Plants, and Organ Fusions between the Stems of a Transgenic Plant.

(A) Col-0/gl1. Outer wall of an epidermal cell with cuticle of uniform structure (arrowheads) overlying the cell wall polysaccharides. .

(B) Cutinase-expressing Col-0/gl1. In contrast to the control, the contact zone between the cell wall polysaccharides and the cuticle was interrupted (arrows). Cuticular material accumulated in highly variable amounts, from apparently none to aggregates of mixed composition. Amorphous material of cuticular origin (solid arrowheads) was interspersed with polysaccharide microfibrils (concave arrowheads) in a loosely structured cuticle. .

(C) Cutinase-expressing Col-0/gl1. Fusion between two stems, overview. Apparently empty spaces surrounded by polysaccharidic cell wall materials characterize the fusion zone at most places (arrows). Areas containing small amounts of cuticular material can also be seen (solid arrowhead). At some places, the cuticle was interrupted and the cell walls of both epidermal cells came into direct contact (concave arrowhead). .

(D) Cutinase-expressing Col-0/gl1. Fusion between two stems. Two stomatal guard cells (g) were present in fused epidermal cell layers. Apparently empty spaces surrounded by polysaccharidic cell wall materials characterized this fusion zone (arrow). .

(E) Cutinase-expressing Col-0/gl1. Enlarged view of detail in (D). At this magnification, a large part of the materials in the fusion zone can be seen to have a fibrillar ultrastructure and to resemble cell wall polysaccharides (concave arrowhead). Waxy compounds were at least partially extracted during the dehydration and embedding procedures. .