Order: Ustilaginales
Like the rust fungi, the smut fungi
are all parasites of vascular plants, and produce basidiospores on transversely
septate basidia arising from overwintering teliospores. But the two groups
differ in many respects, as the Table shows.
Family
Ustilaginaceae
They are
called smut because at most life cycle, they form dry, dusty, smutty masses of
spores, teliospores, sometimes referred to as chlamydospores. In this group the
teliospore is equivalent to that of a rust fungus, so the hypha arising from a
germinating teliospore of a Ustilagobecomes 3-septate, and buds off a yeast-like basidiospore from each compartment
(produce their basidia from germinating teliospores). Compatible elements soon
fuse to restore the dikaryon . Many smut fungi are heterothallic, so fusions
must be between cells of different and compatible parents.
Many other
smuts are also organ-specific: in corn smut, caused by Ustilago maydis, some kernels are
replaced by grossly swollen masses of black teliospores.