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A Microbial Biorealm page on the genus Ustilago


Higher order taxa

Eukaryota; Fungi; Basidiomycota; Ustilaginomycetes; Ustilaginomycetidae; Ustilaginales; Ustilaginaceae; Ustilago


Ustilago maydis (zeae is obsolete name), U. scitaminea (cane smut), U. lituana (grass smut), U. violacea, U. scabiosae, U. utriculosae, U. sphaerogena, U. bullata, U. nigra, U. hordei, U. heterogena

Description and significance

The basidomyctete fungus, Ustilago maydis, is a type of yeast that most commonly inhabits soil or plant environments particularly that are dead. However, it is known as a dimorphic fungus since it can grow in two manners; one is the single-celled form on dead plants and the other is a filamentous mycelial form during the invasion of a plant and also during mating. Nonetheless it is viewed as a pathogen of seeds and flowers of cereals, wheat, corn, and grasses. Typically it can most often be found affecting sweet corn (CWBInfo, 1999-2001). The most prominent feature of its infection on corn is its tumor-like structures that form on the aerial parts of the plant. Plants having these features are characterized as having smut disease.

Ustilago maydis is used often for its homeopathic remedies for the female genitalia. Common uses are for irritation of the ovaries, dark periods, non-menstrual bleeding (passive, non-passive, string bleeding), and pain in the ovaries or the womb, which includes cramping (ABC 2001-04). Some strains of the fungal pathogen emit killer toxins, such as KP6, which are further encoded by double-stranded RNA viruses in its cell cytoplasm (Li, 1999). It also is an excellent model used in analyzing phytopathogenesis in the molecular laboratory.

Even though it is a fungus, it doesn’t have all negative effects. Corn smut is a delicacy in Mexico. This dish is called huitlacoche, which is created before the teliospores are ripe and the inside is moist with the gall being white to gray on the outside. Farmers appreciate this fungus because they can receive a high price relative to unaffected corn crop. Some farmers will introduce this fungus to their crops on purpose (Volk, 1998).

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?

Cell structure and metabolism

Interesting features of cell structure; how it gains energy; what important molecules it produces.


Habitat; symbiosis; contributions to the environment.


How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Current Research

Enter summarries of the most rescent research here--at least three required


[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Dr. Kirk Bartholomew