Glaucophyte

The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of freshwater unicellular algae,[1] less common today than they were during the Proterozoic.[2] Only 15 species have been described, but more species are likely to exist.[3] Together with the red algae (Rhodophyta) and the green algae plus land plants (Viridiplantae or Chloroplastida), they form the Archaeplastida. However, the relationships among the red algae, green algae and glaucophytes are unclear,[4] in large part due to limited study of the glaucophytes.[5]

Glaucophyta
Glaucocystis sp.
Scientific classification
(unranked): Archaeplastida
Division: Glaucophyta
Skuja 1948
Class
  • Glaucocystophyceae Schaffner 1922
Synonyms
  • Glaucocystophyta Kies & Kremer, 1986

The glaucophytes are of interest to biologists studying the development of chloroplasts because some studies suggest they may be similar to the original algal type that led to green plants and red algae in that they may be basal Archaeplastida.[1][6]

Unlike red and green algae, glaucophytes only have asexual reproduction.[7]

Characteristics

The chloroplasts of glaucophytes are known as 'muroplasts',[8] 'cyanoplasts', or 'cyanelles'. Unlike the chloroplasts in other organisms, they have a peptidoglycan layer, believed to be a relic of the endosymbiotic origin of plastids from cyanobacteria.[1][9] Glaucophytes contain the photosynthetic pigment chlorophyll a.[1] Along with red algae[1] and cyanobacteria, they harvest light via phycobilisomes, structures consisting largely of phycobiliproteins. The green algae and land plants have lost that pigment.[10] Like red algae, and in contrast to green algae and plants, glaucophytes store fixed carbon in the cytosol.[11]

Glaucophytes have mitochondria with flat cristae, and undergo open mitosis without centrioles. Motile forms have two unequal flagella, which may have fine hairs and are anchored by a multilayered system of microtubules, both of which are similar to forms found in some green algae.[10]

Classification

Phylogeny of Glaucocystophyceae.[12]

Glaucocystophyceae
Cyanophoraceae

Cyanophora

 
 
Gloeochaetaceae
 

Cyanoptyche

 
 

Gloeochaete

 
 
Glaucocystidaceae
 

Glaucocystopsis

 
 

Glaucocystis

 
 
 
 

Only 13 species of glaucophytes are known, none of which is particularly common in nature.[1] The five included genera are:

  • Phylum Glaucophyta Skuja 1948
    • Class Glaucocystophyceae Schaffner 1922 [Cyanophorophyceae]
      • Order Cyanophorales Kies & Kramer 1986
        • Family Cyanophoraceae Kies & Kramer 1986
          • Genus ?Peliaina Pascher 1929
            • Peliaina cyanea Pascher 1929
          • Genus ?Strobilomonas Schiller 1954
            • Strobilomonas cyaneus Schiller 1954
          • Genus Cyanophora Korshikov 1924 (is motile and lacks a cell wall)
            • C. tetracyanea Korshikov 1941
            • C. biloba Kugrens et al. 1999
            • C. sudae Takahashi & Nozaki 2014
            • C. paradoxa Korshikov 1924
            • C. kugrensii Takahashi & Nozaki 2014
            • C. cuspidata Takahashi & Nozaki 2014
      • Order Gloeochaetales Kies & Kremer 1986
        • Family Gloeochaetaceae Bohlin 1901 ex Skuja 1954
          • Genus Cyanoptyche Pascher 1929 (is the least studied of the four genera)
            • Cyanoptyche gloeocystis Pascher 1929
          • Genus Gloeochaete von Lagerheim 1883 [Schrammia Dangeard 1889 non Britton & Rose 1930 non Guppy 1895; Cyanochaete Gobi 1916] (has both motile and immotile stages, and its cell wall does not appear to be composed of cellulose)
            • G. protogenita Kutzing
            • G. wittrockiana von Lagerheim 1883
      • Order Glaucocystales Bessey 1907
        • Family Glaucocystidaceae Bohlin 1901 ex West 1904
          • Genus Glaucocystopsis Bourrelly 1961
            • Glaucocystopsis africana Bourrelly 1961
          • Genus Glaucocystis Itzigsohn 1868 (is immotile, though it retains very short vestigial flagella, and has a cellulose wall)
            • G. bullosa (Kützing 1836) Wille 1919
            • G. caucasica Tarnogradskii 1957
            • G. cingulata Bohlin 1897
            • G. duplex Prescott 1944
            • G. molochinearum Geitler
            • G. simplex Tarnogradskii 1959
            • G. nostochinearum Itzigsohn 1868 ex Rabenh. 1935
            • G. geitleri Pringsheim 1958 ex Takahashi & Nozaki 2016
            • G. incrassata (Lemmermann 1908) Takahashi & Nozaki 2016
            • G. miyajii Takahashi & Nozaki 2016
            • G. bhattacharyae Takahashi & Nozaki 2016
            • G. oocystiformis Prescott 1944

The glaucophytes were considered before as part of family Oocystaceae, in the order Chlorococcales.[13]

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References
  1. Patrick J. Keeling (2004). "Diversity and evolutionary history of plastids and their hosts". American Journal of Botany. 91 (10): 1481–1493. doi:10.3732/ajb.91.10.1481. PMID 21652304.
  2. Evolutionary Biology: A Plant Perspective
  3. The monoplastidic bottleneck in algae and plant evolution | Journal of Cell Science
  4. Jeffrey D. Palmer, Douglas E. Soltis & Mark W. Chase (2004). "The plant tree of life: an overview and some points of view". American Journal of Botany. 91 (10): 1437–1445. doi:10.3732/ajb.91.10.1437. PMID 21652302.
  5. Dawkins, Richard; Wong, Yan (2016). The Ancestor's Tale. ISBN 978-0544859937.
  6. Eunsoo Kim & Linda E. Graham (2008). Redfield, Rosemary Jeanne (ed.). "EEF2 Analysis Challenges the Monophyly of Archaeplastida and Chromalveolata". PLoS ONE. 3 (7): e2621. doi:10.1371/journal.pone.0002621. PMC 2440802. PMID 18612431.
  7. Plants: A Very Short Introduction
  8. Wise, edited by Robert R.; Hoober, J. Kenneth (2006). The structure and function of plastids. Dordrecht: Springer. pp. 3–21. ISBN 978-1-4020-4061-0.CS1 maint: extra text: authors list (link)
  9. Miyagishima, Shin-ya; Kabeya, Yukihiro; Sugita, Chieko; Sugita, Mamoru; Fujiwara, Takayuki (2014). "DipM is required for peptidoglycan hydrolysis during chloroplast division". BMC Plant Biology. 14: 57. doi:10.1186/1471-2229-14-57. PMC 4015805. PMID 24602296.
  10. Skuja, A. (1948). Taxonomie des Phytoplanktons einiger Seen in Uppland, Schweden. Symbolae Botanicae Upsalienses 9(3): 1-399.Guiry, M.D.; Guiry, G.M. (2020). "Glaucophyta". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.
  11. Ball, S.; Colleoni, C.; Cenci, U.; Raj, J. N.; Tirtiaux, C. (10 January 2011). "The evolution of glycogen and starch metabolism in eukaryotes gives molecular clues to understand the establishment of plastid endosymbiosis". Journal of Experimental Botany. 62 (6): 1775–1801. doi:10.1093/jxb/erq411. PMID 21220783.
  12. Price, Dana C.; Steiner, Jürgen M.; Yoon, Hwan Su; Bhattacharya, Debashish; Löffelhardt, Wolfgang (2017). "Glaucophyta". Handbook of the Protists. pp. 1–65. doi:10.1007/978-3-319-32669-6_42-1. ISBN 978-3-319-32669-6.
  13. http://cfb.unh.edu/phycokey/Choices/Glaucophyceae/GLAUCOCYSTIS/Glaucocystis_key.html
  • Guiry, M.D.; Guiry, G.M. (2020). "Glaucophyta". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.
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