Ustilaginales

The Ustilaginales are an order of fungi within the class Ustilaginomycetes. The order contained 8 families, 49 genera, and 851 species in 2008.

In 2011, monotypic family Pericladiaceae holding just Pericladium  (with 3 species) was added. Also family Cintractiellaceae was later placed in a monotypic order Cintractiellales  in 2020.

Ustinaginales is also known and classified as the smut fungi. They are serious plant pathogens, with only the dikaryotic stage being obligately parasitic.

Morphology
Has a thick-walled resting spore (teliospore), known as the "brand" (burn) spore or chlamydospore.

Economic importance
They can infect corn plants (Zea mays) producing tumor-like galls that render the ears unsaleable. This corn smut, is also known as huitlacoche and sold canned for consumption in Latin America.

Sexual reproduction
Almost all Ustilaginales species share a dimorphic life cycle that includes an asexual, saprophitic yeast-like stage and a filamentous sexual stage that is required to parasitize a host. The parasitic phase involves karyogamy, the process of fusing two haploid nuclei (present in haploid teliospore cells), followed by meiosis. Each meiosis results in a septated basidium bearing four haploid basidiospores which can then proceed to yeast-like growth. During meiosis, genes are expressed that function in recombination and DNA repair.