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Home • Basidioascus undulatus
Photo by Hai D.T. Nguyen
Photo by Hai D.T. Nguyen

Basidioascus undulatus was originally described by Matsushima (2003) as an Ascomycete from soil and was recently re-classified as a Basidiomycete in a new order, Geminibasidiales, by Nguyen et al (2013). The Geminibasidiales are currently the closest order to the Wallemiales and together they form the earliest diverging lineage in Agaricomycotina. The fungi in these groups differ morphologically but they are united by their xerotolerant or xerophilic ecology and an absence of sexual fruiting bodies in culture.

Basidioascus undulatus can be isolated by heat treating soil. It grows as a white colony and possesses a unique ontogenesis where basidia are forcibly discharged upon maturation. Basidia produce a single mature brown basidiospore attached by a sterigma. It also produces a simple asexual stage on some media with chains of thallic, single-celled conidia.

The genome of the ex-type strain of B. undulatus (DAOM 241956) was sequenced with the Illumina paired end technology. Basidioascus undulatus was the first species in the order Geminibasidiales to be sequenced and could serve as a tool for evolution or genetic studies. Its extremophilic ecology, peculiar sporulation behaviour, and phylogenetic isolation suggest the possibility for interesting or novel genes.

Other references

Matsuhima T. 2003. Matsushima Mycological Memoirs. Vol. 10. Kobe, Japan: CD-ROM, published by the author. Basidioascus gen. nov. Matsushima Mycol Mem 10:98–104.

Nguyen HDT, Nickerson NL, Seifert KA. 2013. Basidioascus and Geminibasidium: a new lineage of heat-resistant and xerotolerant basidiomycetes. Mycologia 105(5):1231-1250. doi: 10.3852/12-351