Introduction

The differentiation of a plant cell subsequent to its origin in a meristem involves the alteration of its surface in terms of both cell shape and molecular composition. It is the anatomical complexity resulting from the highly ordered arrangement of differing cell morphologies that we can perceive as cell and tissue patterns. A useful starting point in understanding the mechanisms that lie behind the development of such complexity is to identify changes in the cell wall associated with these diverging cell morphologies and fates. Although the molecular architecture of the plant cell wall principally involves the organisation of polysaccharides there is an increasing awareness that glycoconjugates, although less abundant than polysaccharides, are likely to be extremely important for the integration of wall functions and cellular processes.

When considering cell surface glycoproteins it is useful to consider those associated with the outer face of the plasma membrane in addition to those clearly occurring in the wall. It is molecules at this location that will be involved in wall–cytoplasm interactions and are thus likely to mediate the assembly of specific wall architectures. In many cases we do not yet fully understand the functions of cell surface proteins in a biochemical or a developmental sense; the most abundant classes of surface proteins are still currently named in relation to aspects of their protein or carbohydrate structure. At this stage it is possible only to categorise their roles broadly as structural, enzymic or signalling.