Corn smut ( Ustilago maydis )

Ustilaginomycotina is a subdivision of Mushroom Fungi ( Basidiomycota ) with around 1,500 species. With them are obligate parasites, mostly on plants, only Malassezia parasitized animals. Your name have the types of the dark spores, which infested plant parts look like burnt.


Diagnostic features for the sub-division is a 5S RNA type B, and a cell wall, which is characterized by domination of glucose and absence of xylose.

The species are dimorphisch: You have a haploid phase that grows yeast -like and saprobiontisch lives and a dikaryotic phase forming hyphae and parasitic lives. Not all representatives form teliospores, here smut spores. They are absent in Graphiola, Exobasidium, Microstroma and some smaller genera.

The Septalporen are enclosed on both sides of membrane caps, a feature that distinguishes them from the other two groups of mushrooms or toadstools. In the interaction zone with the host, there are deposits that date back to exocytosis of primary interaction vesicles.

Life cycle

The characteristic life cycle of Ustilaginomycotina species is as follows: The basidiospores germinate and form yeast-like stages that live saprobiontisch. When meeting with a compatible cell occurs by conjugation to form a few multinucleated ( dikaryotic ) cell that grows into a dikaryiotischen mycelium. This mycelium lives parasitically. The infection of the host plant is only dikaryotic cells possible. The mycelium forms probasidia, the teliospores. These are usually thick-walled and detached from the mycelium. The teliospores are formed in the parenchyma of different organs of the host: in roots, stems, leaves, inflorescences, anthers and ovules. The teliospores have a powdery consistency and dark brown to black color, which is why they are also called smut spores. In the teliospores it comes to nuclear pairing and subsequently to meiosis, when germination results in a basidium with four basidiospores.


The vast majority of Ustilaginomycotina species parasitized flowering plants. Malassezia lives on the skin of warm-blooded animals including humans. Two types Melaniella parasitize ferns moss, a type of Exoteliospora on ferns and two types of Uleiella on conifers. All other parasites on flowering plants, including primarily on monocots: 57 % of the species parasitizes grasses, 12% sedges. Species with teliospores parasitize this herbaceous plants, those without teliospores (about Nacktbasidienartige ( Exobasidiales ) and representatives of the Microstromatales ) woody plants


The species form a monophyletic group Ustilaginomycotina one of the three subdivisions of Mushroom Fungi ( Basidiomycota ). They themselves are divided into two classes with several orders:

  • Order Malasseziales

The subdivision of Ustilaginomycotina in holobasidiate fire Fungal ( Ustilaginales ) and phragmobasidiate Tilletiales goes back to Louis René and Charles Tulasne (1847 ).


Pictures of Ustilaginomycotina