The plasmodiophores (also known as plasmophorids or plasmodiophorids) are a group of obligate endoparasitic protists belonging to the subphylum

Endomyxa Endomyxa is a subphylum of Rhizaria The Rhizaria are an ill-defined but species-rich supergroup of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus Paulinella in the phylum Cercozoa, they are a ...

in Cercozoa. Taxonomically, they are united under a single family Plasmodiophoridae, order Plasmodiophorida, sister to the

phagomyxid Phagomyxids are a group of obligate endoparasitic protists belonging to the subphylum Endomyxa in Cercozoa. Taxonomically, they are united under a single family Phagomyxidae, order Phagomyxida, sister to the plasmodiophores. Ecology Phagomyx ...

Ecology and pathology

Plasmodiophores are pathogenic for a wide range of organisms, but mainly

green plants Viridiplantae (literally "green plants") are a clade of eukaryotic organisms that comprise approximately 450,000–500,000 species and play important roles in both terrestrial and aquatic ecosystems. They are made up of the green algae, which ...

. The more commonly recognized are agents of plant diseases such as

clubroot Clubroot is a common disease of cabbages, broccoli, cauliflower, Brussels sprouts, radishes, turnips, stocks, wallflowers and other plants of the family Brassicaceae (Cruciferae). It is caused by ''Plasmodiophora brassicae'', which was once cons ...

powdery scab Powdery scab is a disease of potato tubers. It is caused by the cercozoan ''Spongospora subterranea'' f. sp. ''subterranea'' and is widespread in potato growing countries. Symptoms of powdery scab include small lesions in the early stages of th ...

and

crook root of watercress Crook is another name for criminal. Crook or Crooks may also refer to: Places * Crook, County Durham, England, a town * Crook, Cumbria, England, village and civil parish * Crook Hill, Derbyshire, England * Crook, Colorado, United States, ...

, or vectors for

viruses A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's ...

that infect

beets The beetroot is the taproot portion of a beet plant, usually known in North America as beets while the vegetable is referred to as beetroot in British English, and also known as the table beet, garden beet, red beet, dinner beet or golden beet ...

peanut The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible seeds. It is widely grown in the tropics and subtropics, important to both small and ...

monocots Monocotyledons (), commonly referred to as monocots, ( Lilianae '' sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...

and potatoes, such as the

potato mop-top virus ''Potato mop-top virus (PMTV)'' is a plant pathogenic virus transmitted through the vector ''Spongospora subterranea'' that affects potatoes. PMTV belongs to family of ''Virgaviridae'', and the genus ''Pomovirus'' (Potato mop-top virus). The viru ...

or the

beet necrotic yellow vein virus Beet necrotic yellow vein virus (BNYVV) is a plant virus, transmitted by the plasmodiophorid '' Polymyxa betae.'' The BNYVV is a member of the genus '' Benyvirus'' and is responsible for rhizomania, a disease of sugar beet (Rhizo: root; Mania: m ...

Taxonomy

History

The plasmodiophores have historically been regarded as

Fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

. The first description of plasmodiophores as a taxonomic group was in 1885 by Zopf, who united two genera ''

Plasmodiophora ''Plasmodiophora'' is a genus in the phylum of cercozoa in the class Phytomyxea. It includes the species ''Plasmodiophora brassicae'', which causes the disease cabbage clubroot Clubroot is a common disease of cabbages, broccoli, cauliflow ...

'' and '' Tetramyxa'' in a common family “Plasmodiophoreæ”, inside the group “Monadineæ”, as part of the division Myxomycetes. The family was renamed “Plasmodiophoraceae” in 1888 by Berlese. In 1892, Engler placed the family in its own class “Plasmodiophorales”, later renamed “Plasmodiophoromycetes” to fit nomenclature standards. In 1969 Whittaker, in his

five-kingdom system In biology, a kingdom is the second highest taxonomic rank, just below domain. Kingdoms are divided into smaller groups called phyla. Traditionally, some textbooks from the United States and Canada used a system of six kingdoms (Animalia, Plan ...

, elevated the group to a separate phylum “Plasmodiophoromycota”, acknowledging them as protists instead of fungi. In 1993

Cavalier-Smith Thomas (Tom) Cavalier-Smith, FRS, FRSC, NERC Professorial Fellow (21 October 1942 – 19 March 2021), was a professor of evolutionary biology in the Department of Zoology, at the University of Oxford. His research has led to disc ...

included the plasmodiophores and their sister group Phagomyxida in their current class,

Phytomyxea The Phytomyxea are a class of parasites that are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. They are divided into the orders Plasmodiophorida (ICZN, or Plasmodiophoromycota, ICBN) and Phag ...

, as part of a

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...

phylum called Opalozoa, which at the time contained a diverse assemblage of unrelated zooflagellates, opalines and proteomyxids. Eventually this phylum was discarded, and the name

Opalozoa Opalozoa is a subphylum of heterotrophic protists of the phylum Bigyra, and is the sister group to Sagenista. Opalozoans are non-photosynthetic heterokonts that are ancestrally phagotrophic but many times have evolved to be osmotrophic sapr ...

was modified to label a group inside the phylum

Bigyra Bigyra is a grouping of heterokont organisms. It includes Bicosoecida, Blastocystis and Labyrinthulida. It has also been described as containing Opalozoa, Bicoecia, and Sagenista. Phylogeny The cladogram below shows the internal relationship ...

containing the opalines, bicosoecids and related organisms. Finally, after

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses, in 2002

placed all

, including plasmodiophores, in the subphylum

, inside the

rhizarian The Rhizaria are an ill-defined but species-rich supergroup of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus Paulinella in the phylum Cercozoa, they are all non-photosynthethic, but many foramin ...

phylum Cercozoa.

Systematics

The number of genera varies between sources. There are three accepted genera in the group according to the

WoRMS Worms may refer to: *Worm, an invertebrate animal with a tube-like body and no limbs Places *Worms, Germany Worms () is a city in Rhineland-Palatinate, Germany, situated on the Upper Rhine about south-southwest of Frankfurt am Main. It had ...

'', '' Spongospora'' and '' Tetramyxa''. Below is a complete list with genera that are not included in the register but appear in relevant sources: *''

Ligniera ''Ligniera'' is a protist genus of the family Plasmodiophoraceae. The genus name of ''Ligniera'' is in honour of Élie Antoine Octave Lignier (1855–1916), who was a French botanist, known for his work in the field of paleobotany. References ...

'' (=''Anisomyxa'' ; ''Rhizomyxa'' ; ''Sorolpidium'' ) *'' Membranosorus'' *'' Octomyxa'' *'' Polymyxa'' *''

'' (=''Ostenfeldiella'' ) *'' Sorodiscus'' *'' Sorosphaerula'' (=''Tuburcinia'' ; ''Sorosporium'' ) *'' Spongospora'' (=''Clathrosorus'' ) *'' Tetramyxa'' (=''Molliardia'' ; ''Thecaphora'' ) *'' Woronina''
These genera were once considered plasmodiophores until they were excluded: *'' Cystospora'' – possibly a physiological symptom. *'' Frankiella'' – synonym of the bacteria ''

Frankia ''Frankia'' is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the ''Rhizobium'' bacteria found in the root nodules of legumes in the family Fabaceae. ''Frankia'' also initiate the forming of root ...

''. *'' Peltomyces'' – excluded as unclassifiable. *'' Pyrrhosorus'' – considered Labyrinthulida ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

''.
*'' Sporomyxa'' – excluded as unclassifiable. *'' Trematophlyctis'' – a

chytrid fungus Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek ('), meaning "little pot", describing the structure containing unreleased zoöspores. Chytrid ...

References

{{taxonbar, from1=Q20675797, from2=Q20675800 Cercozoa families Cercozoa orders Endomyxa