Fungalpedia – Note 3326, Ustilaginomycetes
Ustilaginomycetes Warm., Haandb. syst. Bot., Edn 2 (Kjøbenhavn): 57 (1884).
Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank.
Classification: Ustilaginomycotina, Basidiomycota, Dikarya, Fungi.
Free-living saprobic phase with yeast and pathogenic on many plants, typically grasses of the family Poaceae, shrubs, some ferns, and conifers, or parasites on animals. Sexual morph: Sori surrounding stems, inflorescence, ovaries, and organs, long-cylindrical, circular, subcircular, angular to tubular or curved, hypertrophied sometimes bearing small remnants of deformed glumes or as leaf spots, whitish to brown or yellow-green with or without peridium, peridium greyish to brown splitting longitudinally to expose powdery spore mass, sori not usually present in all organs, partitioning cells may be present or absent (Piepenbring 2001; Shivas et al. 2006; McTaggart et al. 2016). Columellae sometimes present or absent, stout or woody, flagelliform or filiform. Spore balls colourless to pigmented, irregular to globose to slightly flattened when connected to adjacent balls, composed of compacted masses of spores, friable or persistent with or without cortex, lobed, and with a central part consisting of parenchymatous sterile cells in the air canals of the mesophyll. Teliospores correspond to probasidia, thick-walled, dark-coloured, sometimes smooth-walled, usually ornamented with warts and ridges, arranged singly or in pairs, multicellular or in pairs, in groups or balls, elongate, globose, subglobose, sometimes broadly ellipsoidal, ovoid, subcuneiform, boomerang shaped, sometimes irregular, collapsed, hemispherically cupped, sub-angular, oblong, club-shaped to oval, three-layered (perisporium, episporium, endosporium), pale olivaceous brown to reddish brown in colour (Rattan et al. 1995; Vánky et al. 2009; Hu et al. 2018). Teliospores germinate into a cylindrical, four-celled basidium that buds as basidiospores. Basidia club-shaped, phragmobasidial, or holobasidial, with or without septa, respectively. Basidiospores numerous, filiform, uninucleate, mostly ballistosporic, and others are passively released (Bauer et al. 2001; Hu et al. 2018). Asexual morph: hyphomycetous or yeast-like. Hyphomycetous Conidiophores solitary or aggregated, semi-macronematous to micronematous. Conidiogenous cells monoblastic, basally clamped, single conidia derived by completely transferring protoplasm. Conidia navicular, obclavate, or fusiform to ellipsoidal on short sterigmata-like structures with 3–4 branches, sometimes narrow at the base, along with many bristle-like distal branches. Chlamydospores sometimes present. (Marvanova and Bandoni 1987; Mekha et al. 2014). Yeast budding yeast-like phase, with the presence of hyphae and pseudohyphae, cells spherical, ellipsoidal to fusoid-shaped on short denticles, cream to light salmon in colour (Piątek et al. 2017).
Life modes and distribution: The members of Ustilaginomycetes are distributed in a wide range of habitats and are reported to follow different life modes (Boekhout 1995; Avis et al. 2001). They are mostly phytopathogenic, mostly infecting members of the grass families Poaceae and Cyperaceae, and are responsible for causing smut diseases and huge economic losses (e.g., Ustilago maydis and U. nuda) (Kruse et al. 2017) (Table 20; Wijayawardene NN et al. 2024). Melanotaenium oreophilum and M. selaginellae are two smuts found to be associated with Selaginella (Bauer et al. 1999). Rarely, some yeast morphs of the members have also been reported to infect humans (Teo and Tay 2006; McNeil and Palazzi 2012) (Table 21; Wijayawardene NN et al. 2024). Some of the members have been isolated from the leaves, fruits, and flowers of plants; there are also reports of isolation from human secretory fluid or blood (Sugita et al. 2003; Arendrup et al. 2014). Moesziomyces antarcticus has been isolated from soil and plants and rarely from human blood (Boekhout 2011). Moesziomyces aphidis was first isolated from an aphid and was later also isolated from water (Boekhout 2011). Rarely, a few species of Ustilaginomycetes parasitize ferns or conifers (Bauer et al. 1999, 2001). Riess et al. (2016) reported Uleiella chilensis to be parasitic on gymnosperms like Araucaria araucana.
Notes: Warming (1884) introduced the class Ustilaginomycetes, of the phylum Basidiomycota. Bauer et al. (1997), on the basis of ultrastructural markers, revealed that Ustilaginomycetes form three lineages belonging to the phyto-parasitic members that lack dolipore with multilayered pore-bearing caps. Bauer et al. (2006) and Hibbett et al. (2007), in their phylogenetic classification of fungi, renamed the clade Ustilaginomycetes as in Kirk et al. (2008) as Ustilaginomycotina to minimize confusion between the names of the taxon and informal terms. Tedersoo et al. (2018), in their classification of the fungi, placed the class Ustilaginomycetes under the subphylum Ustilaginomycotina.
Hyde et al. (2011), in an initial attempt to compile asexually typified genera among the members of the Kingdom Fungi, incorporated anamorphic fungi in the class Ustilaginomycetes according to the natural system of classification. Later, Wijayawardene et al. (2012, 2017b, 2021b) published an updated checklist along with notes and entries on the pleomorphic genera in Ustilaginomycetes. Aime et al. (2018) recommend the use of generic names in place of synonymous alternate asexually typified morph generic names for several members of Ustilaginomycetes, such as Anthracoidea for Crotalia, Mycosarcoma or Ustilago for Pseudozyma, Thecaphora for Rhombiella and Thecaphorella, and Urocystis for Paepalopsis.
According to Kijpornyongpan et al. (2018), the class comprises three orders: Ustilaginales, Urocystidales, and Uleiellales (Bauer et al. 1997; Riess et al. 2016). The order Ustilaginales contains eight families, 49 genera, and 851 species (Kirk et al. 2008). Urocystidales has six families and 400 taxa (Begerow et al. 2006, 2014); and the order Uleiellales is comprised of one family (Uleiellaceae), a single genus (Uleiella), and two species (Riess et al. 2016). There are no recognized subclasses under Ustilaginomycetes.
Many pleomorphic taxa among the members of Ustilaginomycetes have been reported (Kirk et al. 2008). Wang et al. (2015a) proposed taxonomic revisions to adopt one name (between two generic names) when the links between the morphs are confirmed in Ustilaginomycetes. Since the discontinuation of dual names for fungi (Hawksworth et al. 2011), Wang et al. (2015a) and Kruse et al. (2017) have made important publications dealing with the recent nomenclatural changes.
All the members of Ustilaginomycetes are teliosporic, gastroid, and dimorphic (Begerow et al. 2006). Phylogenetic analyses of the rRNA gene (SSU, ITS, LSU, atp6, and tub sequence data) of Hibbett et al. (2007) and Begerow et al. (2006) accommodated this class in subphylum Ustilaginomycotina. He et al. (2019) provided the divergence time estimates for the various orders and families in the class Ustilaginomycetes. According to Wijayawardene et al. (2022a), the class comprises four orders (Uleiellales, Urocystidales, Ustilaginales, and Violaceomycetales), 15 families, and 68 genera. However, two genera, Capitulocladosporium and Eriocortex are classified in Ustilaginomycetes genera incertae sedis.
Type order: Ustilaginales Bek., Kurs Botaniki 1: 221 (1864).
Type family: Ustilaginaceae Tul. & C. Tul. [as ‘Ustilagineae’], Annls Sci. Nat., Bot., sér. 3 7: 14 (1847).
Type genus: Ustilago (Pers.) Roussel, Fl. Calvados, Edn 2: 47 (1806).
Type species: not indicated (see editorial comments in Index Fungorum 2023).
Other accepted species: Species Fungorum – search Ustilaginomycetes.
References
Teo LH, Tay YK. 2006 – Ustilago species infection in humans. BJD 155:1096–1097.
Warming E. 1884 – Haandbog i den systematiske Botanik. ed. 2:1–434.
Entry by
Nalin N. Wijayawardene, Center for Yunnan Plateau Biological Resources Protection and Utilization, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing, Yunnan 655011, P.R. China, Tropical Microbiology Research Foundation, 96/N/10, Meemanagoda Road, 10230 Pannipitiya, Sri Lanka, Department of Bioprocess Technology, Faculty of Technology, Rajarata University, Sri Lanka
Published online 2 October 2026