ABSTRACT
In the previous five chapters, we described in detail the structure and chemistry of the different macromolecules found in plant cell walls, and we saw how the various polymers are made by the cell and then deposited outside the plasma membrane. In this chapter we examine how these polymers, once outside the cell, are assembled into a functional cell wall. We discuss the general architectural principles involved in wall construction, starting with the “glue”: the different ways that wall polymers can be attached to each other through both covalent and noncovalent cross-linkages. We then see how two fundamental networks underlie the construction of all primary cell walls, and how this can be elaborated by the addition of other polymer networks such as protein and lignin. Just as we saw that different cells have appropriately specialized walls, it will become clear that different domains within the wall of an individual cell can also have different compositions and structures. Finally, we show, on a larger scale, how a combination of cell shape, internal turgor pressure, and wall properties contribute to the structural and mechanical properties of plant parts. The differences in texture between a ripe tomato and a crisp apple reside in cell wall properties!
