Chlorophyta

Chlorophyta is a taxon of green algae informally called chlorophytes.[6] The name is used in two very different senses, so care is needed to determine the use by a particular author. In older classification systems, it is a highly paraphyletic group of all the green algae within the green plants (Viridiplantae) and thus includes about 7,000 species[7][8] of mostly aquatic photosynthetic eukaryotic organisms. In newer classifications, it is the sister clade of the streptophytes/charophytes. The clade Streptophyta consists of the Charophyta in which the Embryophyta (land plants) emerged.[9][10] In this latter sense the Chlorophyta includes only about 4,300 species.[4] About 90% of all known species live in freshwater.[11] Like the land plants (embryophytes: bryophytes and tracheophytes), green algae (chlorophytes and charophytes besides embryophytes) contain chlorophyll a and chlorophyll b and store food as starch[7] in their plastids.

This article is about a group of green algae. For the genus with the common name 'spider plant', see Chlorophytum.

Chlorophyta
Chlorophytes (A–F, H–L and O)
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
(unranked): Archaeplastida
(unranked): Viridiplantae
Division: Chlorophyta
Reichenbach, 1828, emend. Pascher, 1914, emend. Lewis & McCourt, 2004[1][2][3]
Classes[4]
Synonyms[5]
  • Chlorophycophyta Papenfuss 1946
  • Chlorophycota
  • Chlorophytina
  • Chlorophyllophyceae
  • Isokontae
  • Stephanokontae
Green algae on coastal rocks at Shihtiping in Taiwan

With the exception of the three classes Ulvophyceae, Trebouxiophyceae and Chlorophyceae in the UTC clade, which show various degrees of multicellularity, all the Chlorophyta lineages are unicellular.[12] Some members of the group form symbiotic relationships with protozoa, sponges, and cnidarians. Others form symbiotic relationships with fungi to form lichens, but the majority of species are free-living. Some conduct sexual reproduction, which is oogamous or isogamous. All members of the clade have motile flagellated swimming cells.[13] While most species live in freshwater habitats and a large number in marine habitats, other species are adapted to a wide range of land environments. For example, Chlamydomonas nivalis, which causes Watermelon snow, lives on summer alpine snowfields. Others, such as Trentepohlia species, live attached to rocks or woody parts of trees. Monostroma kuroshiense, an edible green alga cultivated worldwide and most expensive among green algae, belongs to this group.

Ecology

Species of Chlorophyta (treated as what is now considered one of the two main clades of Viridiplantae) are common inhabitants of marine, freshwater and terrestrial environments.[14][15] Several species have adapted to specialised and extreme environments, such as deserts, arctic environments, hypersaline habitats, marine deep waters, deep-sea hydrothermal vents and habitats that experiences extreme changes in temperature, light and salinity.[16][17][18][19] Some groups, such as the Trentepohliales are exclusively found on land.[20] Several species of Chlorophyta live in symbiosis with a diverse range of eukaryotes, including fungi (to form lichens), ciliates, forams, cnidarians and molluscs. [15] Some species of Chlorophyta are heterotrophic, either free-living or parasitic.[21][22] Others are mixotrophic bacterivores through phagocytosis.[23] Two common species of the heterotrophic green alga Prototheca are pathogenic and can cause the disease protothecosis in humans and animals.[24]

Classifications
"Siphoneae" from Ernst Haeckel's Kunstformen der Natur, 1904
Further information: Wikispecies:Chlorophyta

Characteristics used for the classification of Chlorophyta are: type of zoid, mitosis (karyokinesis), cytokinesis, organization level, life cycle, type of gametes, cell wall polysaccharides[25] and more recently genetic data.

Phylogeny

Leliaert et al. 2012 proposed the following phylogeny. He marked the "prasinophytes" as paraphyletic, with the remaining Chlorophyta groups as "core chlorophytes". He described all Streptophyta except the land plants as paraphyletic "charophytes".[15]

"Hypothetical ancestral
Chlorophyta

Palmophyllales

Prasinococcales

Nephroselmidophyceae

Pycnococcaceae

Pyramimonadophyceae

Mamiellophyceae

Picocystis

Pedinophyceae

Chlorodendrophyceae

Trebouxiophyceae

Ulvophyceae

Chlorophyceae

Streptophyta

Mesostigmatophyceae

Chlorokybophyceae

Klebsormidiophyceae

Charophyceae (stoneworts)

Zygnematophyceae

Coleochaetophyceae

Embryophyte (Land plants)
green flagellate"

A 2020 paper places the "Prasinodermophyta" (i.e. Prasinodermophyceae + Palmophyllophyceae) as the basal Viridiplantae clade.[26]

Viridiplantae/
Prasinodermophyta

Prasinodermophyceae

Palmophyllophyceae

Prasinococcales ("prasinophyte clade VI")

Palmophyllales

Chlorophyta

Pyramimonadophyceae ("prasinophyte clade I")

Mamiellophyceae ("prasinophyte clade II")

Nephroselmidophyceae ("prasinophyte clade III")

Pycnococcaceae ("prasinophyte clade V")

Chloropicophyceae ("prasinophyte clade VII A/B/C")

Tetraphytina

Pedinophyceae

Trebouxiophyceae

Chlorodendrophyceae ("prasinophyte clade IV")

Ulvophyceae

Chlorophyceae

Streptophyta/
Mesostigmatophyceae

Mesostigma viride

Spirotaenia

Chlorokybophyceae

Klebsormidiophyta

Phragmoplastophyta

Charophyceae (stoneworts)

Coleochaetophyceae

Chaetosphaeridiales

Coleochaetophyta

Zygnematophyceae

Zygnematophyta

Mesotaeniaceae

Embryophyte (Land plants)

Charophyta
Green Algae/
Prasinophyta s.l.

Leliaert et al. 2012

Simplified phylogeny of the Chlorophyta, according to Leliaert et al. 2012.[15] Note that many algae previously classified in Chlorophyta are placed here in Streptophyta.

Pombert et al. 2005

A possible classification when Chlorophyta refers to one of the two clades of the Viridiplantae is shown below.[27]

Lewis & McCourt 2004

Hoek, Mann and Jahns 1995

Classification of the Chlorophyta, treated as all green algae, according to Hoek, Mann and Jahns 1995.[7]

In a note added in proof, an alternative classification is presented for the algae of the class Chlorophyceae:

Bold and Wynne 1985

Classification of the Chlorophyta and Charophyta according to Bold and Wynne 1985.[29]

Mattox & Stewart 1984

Classification of the Chlorophyta according to Mattox & Stewart 1984:[28]

Fott 1971

Classification of the Chlorophyta according to Fott 1971.[7]: 483 

  • Suborder Chlorosarcineae
  • Suborder Ulotrichineae
  • Suborder Oedogoniineae
  • Suborder Chaetophorineae

Round 1971

Classification of the Chlorophyta and related algae according to Round 1971.[30]

Smith 1938

Classification of the Chlorophyta according to Smith 1938:

  • Order 5. Schizogoniales
  • Family Schizogoniaceae
  • Order 10. Siphonales
  • Order 11. Siphonocladiales

Research and discoveries

In February 2020, the fossilized remains of green algae, named Proterocladus antiquus were discovered in the northern province of Liaoning, China.[31] At around a billion years old, it is believed to be one of the oldest examples of a multicellular chlorophyte.[32]

References
  1. Reichenbach HG (1828). Conspectus Regni Vegetabilis. p. 23.
  2. Pascher A (1914). "Über Flagellaten und Algen". Berichte der Deutschen Botanischen Gesellschaft. 32: 136–160.
  3. Adl SM, Simpson AG, Farmer MA, Andersen RA, Anderson OR, Barta JR, et al. (2005). "The new higher level classification of eukaryotes with emphasis on the taxonomy of protists". The Journal of Eukaryotic Microbiology. 52 (5): 399–451. doi:10.1111/j.1550-7408.2005.00053.x. PMID 16248873. S2CID 8060916.
  4. Guiry MD, Guiry GM (2011). "AlgaeBase : Chlorophyta". World-wide electronic publication, National University of Ireland, Galway. Retrieved 2011-07-26.
  5. Papenfuss GF (1955). "The Classification of the Algae". A century of progress in the natural sciences, 1853-1953. California Academy of Sciences.
  6. Rockwell NC, Martin SS, Li FW, Mathews S, Lagarias JC (May 2017). "The phycocyanobilin chromophore of streptophyte algal phytochromes is synthesized by HY2". The New Phytologist. 214 (3): 1145–1157. doi:10.1111/nph.14422. PMC 5388591. PMID 28106912.
  7. van den Hoek C, Mann DG, Jahns HM (1995). Algae An Introduction to Phycology. Cambridge: Cambridge University Press. ISBN 978-0-521-30419-1.
  8. "Major Algae Phyla - Table - MSN Encarta". Archived from the original on 2009-10-29.
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  10. Becker B, Marin B (May 2009). "Streptophyte algae and the origin of embryophytes". Annals of Botany. 103 (7): 999–1004. doi:10.1093/aob/mcp044. PMC 2707909. PMID 19273476.
  11. Lee, Robert Edward (2018). Chlorophyta (Chapter 5) - Phycology - Cambridge University Press. doi:10.1017/9781316407219. ISBN 9781316407219.
  12. Umen JG (October 2014). "Green algae and the origins of multicellularity in the plant kingdom". Cold Spring Harbor Perspectives in Biology. 6 (11): a016170. doi:10.1101/cshperspect.a016170. PMC 4413236. PMID 25324214.
  13. Kapraun DF (April 2007). "Nuclear DNA content estimates in green algal lineages: chlorophyta and streptophyta". Annals of Botany. 99 (4): 677–701. doi:10.1093/aob/mcl294. PMC 2802934. PMID 17272304.
  14. Graham LE, Graham JM, Wilcox LW (2009) Algae. 2nd Edition. Benjamin Cummings (Pearson), San Francisco, CA
  15. Leliaert F, Smith DR, Moreau H, Herron MD, Verbruggen H, Delwiche CF, De Clerck O (2012). "Phylogeny and molecular evolution of the green algae" (PDF). Critical Reviews in Plant Sciences. 31: 1–46. doi:10.1080/07352689.2011.615705. S2CID 17603352. Archived (PDF) from the original on 2015-06-26.
  16. Lewis LA, Lewis PO (December 2005). "Unearthing the molecular phylodiversity of desert soil green algae (Chlorophyta)". Systematic Biology. 54 (6): 936–47. doi:10.1080/10635150500354852. PMID 16338765.
  17. De Wever A, Leliaert F, Verleyen E, Vanormelingen P, Van der Gucht K, Hodgson DA, Sabbe K, Vyverman W (October 2009). "Hidden levels of phylodiversity in Antarctic green algae: further evidence for the existence of glacial refugia". Proceedings. Biological Sciences. 276 (1673): 3591–9. doi:10.1098/rspb.2009.0994. PMC 2817313. PMID 19625320.
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  19. Foflonker F, Ananyev G, Qiu H, Morrison A, Palenik B, Dismukes GC, Bhattacharya D (June 2016). "The unexpected extremophile: Tolerance to fluctuating salinity in the green alga Picochlorum". Algal Research. 16: 465–472. doi:10.1016/j.algal.2016.04.003.
  20. López-Bautista JM, Rindi F, Guiry MD (July 2006). "Molecular systematics of the subaerial green algal order Trentepohliales: an assessment based on morphological and molecular data". International Journal of Systematic and Evolutionary Microbiology. 56 (Pt 7): 1709–15. doi:10.1099/ijs.0.63990-0. PMID 16825655.
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  24. Tartar A, Boucias DG, Adams BJ, Becnel JJ (January 2002). "Phylogenetic analysis identifies the invertebrate pathogen Helicosporidium sp. as a green alga (Chlorophyta)". International Journal of Systematic and Evolutionary Microbiology. 52 (Pt 1): 273–9. doi:10.1099/00207713-52-1-273. PMID 11837312.
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  27. Pombert JF, Otis C, Lemieux C, Turmel M (September 2005). "The chloroplast genome sequence of the green alga Pseudendoclonium akinetum (Ulvophyceae) reveals unusual structural features and new insights into the branching order of chlorophyte lineages". Molecular Biology and Evolution. 22 (9): 1903–18. doi:10.1093/molbev/msi182. PMID 15930151.
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  32. Sandhya Ramesh (2020-02-25). "Scientists discover world's oldest green algae fossil in China". ThePrint. Retrieved 2020-02-25.

Further reading
Wikispecies has information related to Chlorophyta.
Wikimedia Commons has media related to Chlorophyta.
  • Burrows EM (1991). Seaweeds of the British Isles. Vol. 2 (Chlorophyta). London: Natural History Museum. ISBN 978-0-565-00981-6.
  • Lewis LA, McCourt RM (October 2004). "Green algae and the origin of land plants". American Journal of Botany. 91 (10): 1535–56. doi:10.3732/ajb.91.10.1535. PMID 21652308.
  • Pickett-Heaps JD (1975). Green Algae. Structure, Reproduction and Evolution in Selected Genera. Stamford, CT: Sinauer Assoc. p. 606.
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