The plasmodiophores (also known as plasmophorids or plasmodiophorids) are a group of

obligate {{wiktionary, obligate As an adjective, obligate means "by necessity" (antonym ''facultative'') and is used mainly in biology in phrases such as: * Obligate aerobe, an organism that cannot survive without oxygen * Obligate anaerobe, an organism tha ...

protists A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...

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 al ...

Cercozoa Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead defined by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major euk ...

. 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 Phagomyxids ...

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 a ...

. The more commonly recognized are agents of plant diseases such as clubroot, powdery scab 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, a ...

, 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,

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 an ...

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 The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern United ...

, such as the potato mop-top virus or the beet necrotic yellow vein virus.

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 fr ...

. The first description of plasmodiophores as a taxonomic group was in 1885 by

Zopf Zopf or Züpfe ( French and in Italian) is a type of Swiss, Austrian, German or Bavarian bread made from white flour, milk, eggs, butter and yeast. The dough is brushed with egg yolk, egg wash, or milk before baking, lending it its golden ...

, who united two genera '' Plasmodiophora'' 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

instead of fungi. In 1993 Cavalier-Smith included the plasmodiophores and their sister group

Phagomyxida 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 Phagomyxids ...

in their current class, Phytomyxea, 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 saprotr ...

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 relationships w ...

containing the opalines,

bicosoecids Bicosoecida (ICZN) or Bicosoecales/Bicoecea (ICBN) is an order of Bikosea, a small group of unicellular flagellates, included among the heterokonts. Informally known as bicosoecids, they are a small group of unicellular flagellates. The cells ar ...

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 ...

analyses, in 2002 Cavalier-Smith placed all Phytomyxea, 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

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 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 the ...

'' and '' Tetramyxa''. Below is a complete list with genera that are not included in the register but appear in relevant sources: *'' Ligniera'' (=''Anisomyxa'' ; ''Rhizomyxa'' ; ''Sorolpidium'' ) *'' Membranosorus'' *'' Octomyxa'' *'' Polymyxa'' *'' Plasmodiophora'' (=''Ostenfeldiella'' ) *'' Sorodiscus'' *'' Sorosphaerula'' (=''Tuburcinia'' ; ''Sorosporium'' ) *''

'' (=''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''. *'' Peltomyces'' – excluded as unclassifiable. *'' Pyrrhosorus'' – considered

Labyrinthulida The Labyrinthulomycetes ( ICBN) or Labyrinthulea (ICZN) are a class of protists that produce a network of filaments or tubes, which serve as tracks for the cells to glide along and absorb nutrients for them. The two main groups are the labyri ...

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.

References

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