Phytomyxea

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Phytomyxea
Phytomyxea collage.jpg
Resting spores of different species
Scientific classification
Domain:
Eukaryota
(unranked):
SAR
(unranked):
Rhizaria
Phylum:
Cercozoa
Subphylum:
Endomyxa
Class:
Phytomyxea

Cavalier-Smith, 1993
Orders
  • Phagomyxida
  • Plasmodiophorida
Synonyms
  • Phytomyxini Schröter, 1886:133
  • Phytomyxinae MacBride 1892:111; 1899:16; Schröter in Engler & Prantl, 1897; Doflein, 1911:672
  • Phytomyxinea Poche 1913:197
  • Phytomixida Calkins, 1926:328
Life cycle of Plasmodiophora brassicae in cabbage.
Clubroot on cauliflower

The Phytomyxea are a class of parasites that are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae.[1] They are divided into the orders Plasmodiophorida (ICZN, or Plasmodiophoromycota, ICBN) and Phagomyxida.[2] 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).[3]

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.[4] These are caused by species of Plasmodiophora and Spongospora, respectively.[5]

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, are closely related to them.

  • Class Phytomyxea Engler & Prantl 1897 em. Cavalier-Smith 1993
    • Genus ?
    • Order Phagomyxida Cavalier-Smith 1993
      • Family Cavalier-Smith 1993
        • Genus Karling 1944
    • Order Plasmodiophorida Cook 1928 em. Cavalier-Smith 1993
      • Family Olive & Erdos 1971
        • Genus Olive & Erdos 1971
      • Family Berl 1888 (plasmodial slime moulds)
        • Genus Elliott 1916 nomen dubium [ Ellis & Halsted ex Halsted 1890 non Zanardini 1872]
        • Genus Maullinia Maier et al. 2000
        • Genus Phytomyxa Schröter 1886
        • Genus Ligniera Maire & Tison 1911 [Anisomyxa Němec 1913; Rhizomyxa Borzí 1884; Němec 1911]
        • Genus Ostenfeld & Petersen 1930
        • Genus Couch, Leitner & Whiffen 1939
        • Genus Plasmodiophora Woronin 1877 [ Maire & Tison 1909 non Speschnew 1900; Frankia Brunchorst 1886 non; Ferdinandsen & Winge 1914]
        • Genus Ledingham 1933
        • Genus Lagerheim & Winge 1913 non Allman 1847
        • Genus Schröter 1886
        • Genus Neuh. & Kirchm. 2011
        • Genus Spongospora Brunchorst 1887 [ Ferdinandsen & Winge 1920]
        • Genus Léger 1908
        • Genus Goebel 1884 [ Maire & Tison 1911]
        • Genus Cornu 1872

References[]

  1. ^ Neuhauser, Sigrid; Kirchmair, Martin; Bulman, Simon; Bass, David (2014). "Cross-kingdom host shifts of phytomyxid parasites". BMC Evolutionary Biology. 14 (1): 33. doi:10.1186/1471-2148-14-33. PMC 4016497. PMID 24559266.
  2. ^ David Bass; Ema E.-Y. Chao; Sergey Nikolaev; Akinori Yabuki; Ken-ichiro Ishida; Cédric Berney; Ursula Pakzad; Claudia Wylezich; Thomas Cavalier-Smith (February 2009). "Phylogeny of novel naked filose and reticulose Cercozoa: Granofilosea cl. n. and Proteomyxidea revised". Protist. 160 (1): 75–109. doi:10.1016/j.protis.2008.07.002. PMID 18952499.
  3. ^ Schwelm, Arne; Badstöber, Julia; Bulman, Simon; Desoignies, Nicolas; Etemadi, Mohammad; Falloon, Richard E.; Gachon, Claire M. M.; Legreve, Anne; Lukeš, Julius; Merz, Ueli; Nenarokova, Anna; Strittmatter, Martina; Sullivan, Brooke K.; Neuhauser, Sigrid (2018). "Not in your usual Top 10: protists that infect plants and algae". Molecular Plant Pathology. 19 (4): 1029–1044. doi:10.1111/mpp.12580. PMC 5772912. PMID 29024322.
  4. ^ Schwelm, Arne; Badstöber, Julia; Bulman, Simon; Desoignies, Nicolas; Etemadi, Mohammad; Falloon, Richard E.; Gachon, Claire M. M.; Legreve, Anne; Lukeš, Julius; Merz, Ueli; Nenarokova, Anna; Strittmatter, Martina; Sullivan, Brooke K.; Neuhauser, Sigrid (2018). "Not in your usual Top 10: protists that infect plants and algae". Molecular Plant Pathology. 19 (4): 1029–1044. doi:10.1111/mpp.12580. PMC 5772912. PMID 29024322.
  5. ^ Agrios, George N. (2005). Plant Pathology. 5th ed. Academic Press. link.
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