The Fungal Wall
- Functions :
- PROTECTS the underlying protoplasm;
- determines and MAINTAINS THE SHAPE of the fungal cell or hypha;
if you remove the wall the resulting protoplast will always
assume a spherical shape;
- acts as an INTERFACE between the fungus and its environment;
- acts as a BINDING SITE for some enzymes;
- possesses ANTIGENIC properties - which allow interactions with other
- Chemical composition of the wall:
- POLYMERIC FIBRILS
- cellulose (in the Oomycota)
- AMORPHOUS MATRIX
- heteropolymers (mixed polymers) of mannose, galactose, fucose and xylose
- The types and amounts of these various components vary amongst different
groups of fungi and may even vary during the life cycle of
a single species.
- Arrangement of the wall components:
- The diagram above represents a section through the mature lateral wall
of hyphae of Neurospora crassa.
- In general, the inner part of the wall consists of POLYMERIC FIBRILS
embedded in an AMORPHOUS MATRIX and this is covered by further
layers of matrix material.
- At the HYPHAL TIP the wall is thinner and simpler in structure, consisting
of only TWO LAYERS - an inner layer of fibrils embedded
in protein and outer layer of mainly protein.
- EXTRA LAYERS of wall material are deposited in the lateral
walls behind the extending apex - strengthening the wall as
the hypha matures.
- In the oldest parts of the hyphae (and in many fungal spores) LIPIDS
and PIGMENTS may be desposited in the wall:
- LIPIDS serve as a nutrient reserve and help prevent desiccation
- PIGMENTS, such as MELANIN, help protect the protoplast against the
damaging effects of UV radiation.
- N.B. Although represented as distinct layers in the diagram above, these
four zones merge into one another.