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 ...

endoparasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

protists A protist ( ) or protoctist is any Eukaryote, eukaryotic organism that is not an animal, Embryophyte, land plant, or fungus. Protists do not form a Clade, natural group, or clade, but are a Paraphyly, paraphyletic grouping of all descendants o ...

belonging to the subphylum

Endomyxa Endomyxa is a group of eukaryotic organisms in the supergroup Rhizaria. They were initially a subphylum of Cercozoa and later a subphylum of Retaria, but several analyses have proven they are a phylogenetically separate lineage, and Endomyxa is ...

Cercozoa Cercozoa (now synonymised with Filosa) is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead united by phylogeny, molecular phylogenies of rRNA and actin or Ubiqu ...

. 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 (; Kingdom (biology), kingdom Plantae ''Sensu#Common qualifiers, sensu stricto'') is a clade of around 450,000–500,000 species of eukaryote, eukaryotic organisms, most of which obtain their energy by photosynthesis. The green pla ...

. 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, Matthiola, stocks, Erysimum, wallflowers and other plants of the family Brassicaceae (Cruciferae). It is caused by ''Plasmodiophora brassicae'' ...

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 the ...

and

crook root of watercress Crook is slang for criminal In ordinary language, a crime is an unlawful act punishable by a State (polity), state or other authority. The term ''crime'' does not, in modern criminal law, have any simple and universally accepted definition,Farm ...

, 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. Viruses are found in almo ...

that infect

beets The beetroot (British English) or beet (North American English) is the taproot portion of a ''Beta vulgaris'' subsp. ''vulgaris'' plant in the Conditiva Group. The plant is a root vegetable also known as the table beet, garden beet, dinner beet ...

peanut The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), goober pea, 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 by small and large ...

monocots Monocotyledons (), commonly referred to as monocots, ( Lilianae '' sensu'' Chase & Reveal) are flowering plants whose seeds contain only one embryonic leaf, or cotyledon. A monocot taxon has been in use for several decades, but with various ranks a ...

and

potatoes The potato () is a starchy tuberous vegetable native to the Americas that is consumed as a staple food in many parts of the world. Potatoes are underground stem tubers of the plant ''Solanum tuberosum'', a perennial in the nightshade famil ...

, such as the

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

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 ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

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

Zopf Zopf (), Butterzopf () or Züpfe () ( in French and in Italian) is a type of Swiss, Austrian, and German bread made from white flour, milk, eggs, butter and yeast. The is typically brushed with egg yolk, egg wash, or milk before baking, le ...

, who united two genera ''

Plasmodiophora ''Plasmodiophora'' is a genus in class Phytomyxea The Phytomyxea are a class (biology), class of parasites that are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. They are divided into the ...

'' 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 Berlese or Berlèse is a surname. Notable people with the surname include: * Antonio Berlese (1863–1927), Italian entomologist * Augusto Napoleone Berlese (1864–1903), Italian botanist and mycologist, brother of Antonio * Lorenzo Berlèse (1 ...

. 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 (singular phylum). Traditionally, textbooks from Canada and the United States have used a system of six kingdom ...

, elevated the group to a separate phylum “Plasmodiophoromycota”, acknowledging them as

instead of fungi. In 1993

Cavalier-Smith Thomas (Tom) Cavalier-Smith, Royal Society, FRS, Royal Society of Canada, FRSC, Natural Environment Research Council, NERC Professorial Fellow (21 October 1942 – 19 March 2021), was a professor of evolutionary biology in the Departme ...

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 The Phytomyxea are a class (biology), class of parasites that are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. They are divided into the orders Plasmodiophorida (International Code of Zoolog ...

, as part of a

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

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 sapro ...

was modified to label a group inside the phylum

Bigyra Bigyra () is a phylum of microscopic eukaryotes that are found at the base of the Stramenopiles clade. It includes three well-known heterotrophic groups Bicosoecida, Opalinata and Labyrinthulomycetes, as well as several small clades initially disc ...

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

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analyses, in 2002

placed all

, including plasmodiophores, in the subphylum

, inside the

rhizaria The Rhizaria are a diverse and species-rich clade of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus '' Paulinella'' in the phylum Cercozoa, they are all non-photosynthetic, but many Foraminifera ...

n phylum

Classification

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

WoRMS The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scien ...

'', ''

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 ''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'' *'' Ostenfeldiella'' *'' Polymyxa'' *''

'' *'' Pseudoligniera'' *'' Sorodiscus'' *'' Sorosphaerula'' (=''Tuburcinia'' ; ''Sorosporium'' ) *''

'' (=''Clathrosorus'' ) *'' Hillenburgia'' *'' 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 ro ...

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

Labyrinthulida Labyrinthulomycetes (ICNafp) or Labyrinthulea (ICZN) is 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 labyrinthul ...

incertae sedis or is a term used for a taxonomy (biology), 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, uncertainty ...

''. *'' 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 zoospores. Chytrids ...

References

{{taxonbar, from1=Q20675797, from2=Q20675800, from3=Q15241144, from4=Q15241146 Endomyxa