Evolution of Fungi and Fungal-Like Organisms

Volume 14 of the series The Mycota pp 97-160


6 Mating Type in Basidiomycetes: Unipolar, Bipolar, and Tetrapolar Patterns of Sexuality

  • Ursula KüesAffiliated withDivision of Molecular Wood Biotechnology and Technical Mycology, Büsgen-Institute, University of Göttingen Email author 
  • , Timothy Y. JamesAffiliated withDepartment of Ecology and Evolutionary Biology, University of Michigan
  • , Joseph HeitmanAffiliated withDepartment of Molecular Genetics and Microbiology, Duke University Medical Center

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We summarize current knowledge on the structure of mating type loci in different species of basidiomycetes, giving special consideration to bipolar and tetrapolar heterothallic species. In all three subphyla of the Basidiomycota, heterothallic bipolar, heterothallic tetrapolar, and homothallic species have been described, and in all subphyla, there are evidently also anamorphic (asexual) species. Generally, a multitude of different insights on mating type genes and their evolution have now been revealed in different basidiomycete species using both model and non-model species and molecular and evolutionary genetics. The existing data suggest that multiple mating types have evolved only once in fungi, being restricted to Basidiomycota. We introduce a new term, unipolarity, to describe the unisexual mode of fungal reproduction that is distinguished from the bipolar and tetrapolar configurations. The existence of facultative unipolarity within heterothallic species may have been largely ignored in the past but merits further investigation.