Basidiomycota
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 Basidiomycetes from Ernst Haeckel's 1904 Kunstformen der Natur
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Subdivision Teliomycotina |
The Division Basidiomycota is a large taxon within the Kingdom Fungi that includes those species that produce spores in a club-shaped structure called a basidium. Essentially the sibling group of the Ascomycota, it contains some 22,300 distinct species (out of an estimated total of 1.5 million fungal species). The Basidiomycota was traditionally divided into Homobasidiomycetes (the true mushrooms); and Heterobasidiomycetes (the Jelly, Rust and Smut fungi). The Basidiomycota is now thought to comprise four major clades, the Hymenomycotina (Hymenomycetes; mushrooms), the Ustilaginomycotina (Ustilaginomycetes; true smut fungi), and the Teliomycotina (Urediniomycetes; rusts).
Basidiomycota can exist in both unicellular (some yeasts) and multicellular forms, and may reproduce either sexually or asexually. They occur in terrestrial and aquatic environments (including the marine environment) and can be characterized by bearing sexual spores on basidia, the gill-like structures under the mushroom head. Other notable characteristics include a long-lived dikaryon, and the presence of clamp connections.
[edit] Life cycle
Basidiomycetes have an abnormal sexuality. They most often are heterothallic, but with a bipolar (unifactorial) or tetrapolar (bifactorial) mating system acting like many sexes[1]. Usually, somatogamy (hyphogamy) is performed.
Most basidiomycetes live out most of their life as dikaryotic (heterokaryotic) mycelium, with reproduction happenning in the basidium. Reproduction can either occur by the fusion of the nuclei of two cells (karyogamy) or by meiosis. There are examples of diploid life cycles as well: the genus Xerula was found to sometimes produce diploid clones as spores, and Armillaria, a common forest pathogen, has diploid mycelium, where karyogamy directly follows plasmogamy. Asexual spores (conidia) are more and more being discovered also in the basidiomycetes.
[edit] References
- ^ Hall, Avice (Feb 2006). Reproduction. Web Resource Handbook of Fungi. University of Hertfordshire. Retrieved on 22-Jan-2007.
[edit] External links
- Basidiomycota at the Tree of Life Web Project
