{{Short description|Class of protists}} {{Automatic taxobox | image = Phytomyxea collage.jpg | image_caption = Resting spores of different species | taxon = Phytomyxea | authority = Cavalier-Smith, 1993 | subdivision_ranks = Orders | subdivision = * Phagomyxida * Plasmodiophorida | synonyms = * Phytomyxini <small>Schröter, 1886:133</small> * Phytomyxinae <small>MacBride 1892:111; 1899:16; Schröter in Engler & Prantl, 1897; Doflein, 1911:672</small> * Phytomyxinea <small>Poche 1913:197</small> * Phytomixida <small>Calkins, 1926:328</small> }} [[File:08 08 life cycle, Plasmodiophora brassicae in cabbage, Plasmodiophoromycetes (M. Piepenbring).png|thumb|right|Life cycle of ''Plasmodiophora brassicae'' in cabbage.]] 220px|thumb|Clubroot on cauliflower
The '''Phytomyxea''' are a class of parasites that are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae.<ref>{{cite journal |last1=Neuhauser |first1=Sigrid |last2=Kirchmair |first2=Martin |last3=Bulman |first3=Simon |last4=Bass |first4=David |title=Cross-kingdom host shifts of phytomyxid parasites |journal=BMC Evolutionary Biology |date=2014 |volume=14 |issue=1 |pages=33 |doi=10.1186/1471-2148-14-33|pmid=24559266 |pmc=4016497 |doi-access=free |bibcode=2014BMCEE..14...33N }}</ref> They are divided into the orders Plasmodiophorida (ICZN, or Plasmodiophoromycota, ICBN) and Phagomyxida.<ref name="pmid18952499">{{cite journal |author1=David Bass |author2=Ema E.-Y. Chao |author3=Sergey Nikolaev |author4=Akinori Yabuki |author5=Ken-ichiro Ishida |author6=Cédric Berney |author7=Ursula Pakzad |author8=Claudia Wylezich |author9=Thomas Cavalier-Smith |title=Phylogeny of novel naked filose and reticulose Cercozoa: Granofilosea cl. n. and Proteomyxidea revised |journal=Protist |volume=160 |issue=1 |pages=75–109 |date=February 2009 |pmid=18952499 |doi=10.1016/j.protis.2008.07.002 }}</ref> Plasmodiophorids are best known as pathogens or vectors for viruses of arable crops (e.g. club root in Brassicaceae, powdery scab in potatoes, and rhizomania in beets, especially sugar beets and some spinaches).<ref>{{cite journal |last1=Schwelm |first1=Arne |last2=Badstöber |first2=Julia |last3=Bulman |first3=Simon |last4=Desoignies |first4=Nicolas |last5=Etemadi |first5=Mohammad |last6=Falloon |first6=Richard E. |last7=Gachon |first7=Claire M. M. |last8=Legreve |first8=Anne |last9=Lukeš |first9=Julius |last10=Merz |first10=Ueli |last11=Nenarokova |first11=Anna |last12=Strittmatter |first12=Martina |last13=Sullivan |first13=Brooke K. |last14=Neuhauser |first14=Sigrid |title=Not in your usual Top 10: protists that infect plants and algae |journal=Molecular Plant Pathology |date=2018 |volume=19 |issue=4 |pages=1029–1044 |doi=10.1111/mpp.12580|pmid=29024322 |pmc=5772912 |bibcode=2018MolPP..19.1029S }}</ref>
==Life cycle== They typically develop within plant cells, causing the infected tissue to grow into a gall or scab. Important diseases caused by phytomyxeans include club root in cabbage and its relatives, and powdery scab in potatoes.<ref>{{cite journal |last1=Schwelm |first1=Arne |last2=Badstöber |first2=Julia |last3=Bulman |first3=Simon |last4=Desoignies |first4=Nicolas |last5=Etemadi |first5=Mohammad |last6=Falloon |first6=Richard E. |last7=Gachon |first7=Claire M. M. |last8=Legreve |first8=Anne |last9=Lukeš |first9=Julius |last10=Merz |first10=Ueli |last11=Nenarokova |first11=Anna |last12=Strittmatter |first12=Martina |last13=Sullivan |first13=Brooke K. |last14=Neuhauser |first14=Sigrid |title=Not in your usual Top 10: protists that infect plants and algae |journal=Molecular Plant Pathology |date=2018 |volume=19 |issue=4 |pages=1029–1044 |doi=10.1111/mpp.12580|pmid=29024322 |pmc=5772912 |bibcode=2018MolPP..19.1029S }}</ref> These are caused by species of ''Plasmodiophora'' and ''Spongospora'', respectively.<ref>Agrios, George N. (2005). ''Plant Pathology''. 5th ed. Academic Press. [https://books.google.com/books?id=CnzbgZgby60C link].</ref>
The vegetative form is a multinucleate cell, called a plasmodium. This ultimately divides to form new spores, which are released when the host's cells burst. Both resting spores and motile zoospores, which generally have two smooth flagella, are produced at different stages. Within the plasmodium, dividing nuclei have a distinctive cross-like appearance.
==Classification== Plasmodiophorids were traditionally considered slime moulds, because of the plasmodial stage and are often wrongly classified as fungi, and given names such as the Plasmodiophoromycota. However, genetic and ultrastructural studies indicate they belong to a diverse group of protists called the Cercozoa, and are not closely related to fungi.
* Class '''Phytomyxea''' <small>Engler & Prantl 1897 em. Cavalier-Smith 1993</small> ** Genus ?''Pongomyxa'' ** Order Phagomyxida <small>Cavalier-Smith 1993</small> *** Family Phagomyxidae <small>Cavalier-Smith 1993</small> **** Genus ''Phagomyxa'' <small>Karling 1944</small> **** Genus ''Maullinia'' <small>Maier et al. 2000</small> ** Order Plasmodiophorida <small>Cook 1928 em. Cavalier-Smith 1993</small> *** Family Endemosarcidae <small>Olive & Erdos 1971</small> **** Genus ''Endemosarca'' <small>Olive & Erdos 1971</small> *** Family Plasmodiophoridae <small>Berl 1888</small> (plasmodial slime moulds) **** Genus ''Cystospora'' <small>Elliott 1916 nomen dubium</small> [''Acrocystis'' <small>Ellis & Halsted ex Halsted 1890 non Zanardini 1872</small>] **** Genus ''Phytomyxa'' <small>Schröter 1886</small> **** Genus ''Ligniera'' <small>Maire & Tison 1911</small> [''Anisomyxa'' <small>Němec 1913</small>; ''Rhizomyxa'' <small>Borzí 1884</small>; ''Sorolpidium'' <small>Němec 1911</small>] **** Genus ''Membranosporus'' <small>Ostenfeld & Petersen 1930</small> **** Genus ''Octomyxa'' <small>Couch, Leitner & Whiffen 1939</small> **** Genus ''Plasmodiophora'' <small>Woronin 1877</small> [''Frankiella'' <small>Maire & Tison 1909 non Speschnew 1900</small>; ''Frankia'' <small>Brunchorst 1886 non</small>; ''Ostenfeldiella'' <small>Ferdinandsen & Winge 1914</small>] **** Genus ''Polymyxa'' <small>Ledingham 1933</small> **** Genus ''Sorodiscus'' <small>Lagerheim & Winge 1913 non Allman 1847</small> **** Genus ''Sorosphaera'' <small>Schröter 1886</small> **** Genus ''Sorosphaerula'' <small>Neuh. & Kirchm. 2011</small> **** Genus ''Spongospora'' <small>Brunchorst 1887</small> [''Clathrosorus'' <small>Ferdinandsen & Winge 1920</small>] **** Genus ''Sporomyxa'' <small>Léger 1908</small> **** Genus ''Tetramyxa'' <small>Goebel 1884</small> [''Molliardia'' <small>Maire & Tison 1911</small>] **** Genus ''Woronina'' <small>Cornu 1872</small>
== References == {{Wikispecies}} {{Reflist}}
{{Rhizaria}} {{Taxonbar|from=Q134349}}
Category:Endomyxa Category:Parasitic Rhizaria Category:Parasites of plants Category:Rhizaria classes