Wall Structure, Wall Growth, and Fungal Cell Morphogenesis

Abstract

Because of its rigidity, the wall maintains the shape of the fungal hypha and various arguments have indicated chitin microfibrils embedded in an amorphous matrix as the major polymeric assemblage conferring rigidity to the wall (Bartnicki-Garcia 1973; Burnett 1979; Gooday and Trinci 1980; Wessels and Sietsma 1981). This rigidity contrasts with the need for expansion of the wall when growth occurs either apically, as in all vegetatively growing hyphae, or by diffuse extension, as in hyphae in some fruit bodies. To accommodate these contrasting needs, two basic hypotheses have been advanced. Either the wall as synthesized is inherently rigid and must be continuously loosened by lysins in order to expand and to allow for intercalation of new polymers. Alternatively, the newly synthesized wall is inherently visco-elastic and expandable and gradually develops rigidity to fulfill its role in the mature wall.