Biology:Prasinophyceae

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Short description: Class of algae

Prasinophyceae
Pyramimonas sp color.jpg
Pyramimonas sp.
Scientific classification
Kingdom:
Viridiplantae
Division:
Chlorophyta
Class:
Prasinophyceae

T.Christensen ex P.C.Silva 1980
Orders[1]

The prasinophytes are a group of unicellular green algae.[clarification needed][2] Prasinophytes mainly include marine planktonic species, as well as some freshwater representatives.[2][3] The prasinophytes are morphologically diverse, including flagellates with one to eight flagella and non-motile (coccoid) unicells. The cells of many species are covered with organic body scales; others are naked.[3] Well studied genera include Ostreococcus, considered to be the smallest (ca. 0.95 μm) free-living eukaryote,[4] and Micromonas, both of which are found in marine waters worldwide. Prasinophytes have simple cellular structures, containing a single chloroplast and a single mitochondrion. The genomes are relatively small compared to other eukaryotes (about 12 Mbp for Ostreococcus[5][6] and 21 Mbp for Micromonas[7]). At least one species, the Antarctic form Pyramimonas gelidicola, is capable of phagocytosis and is therefore a mixotrophic algae.[8]

Some authors treat the prasinophytes as a polyphyletic grouping of green algae from different clades. As the Tetraphytina emerged in the Prasinophytes, recently authors include it, rendering it monophyletic, and equivalent to chlorophyta.[9][10]

Ecology

Micromonas pusilla

A study of photosynthetic gene-sequence diversity (rbcL) in the Gulf of Mexico indicated that Prasinophytes are particularly prevalent at the Subsurface Chlorophyll Maximum (SCM)[11] and several different ecotypes of Ostreococcus have been detected in the environment.[12] These ecotypes were thought to be distinguished in the environment by their adaptation to light intensities. O. lucimarinus was isolated from a high-light environment[13] and observed year-round in the coastal North Pacific Ocean.[14] RCC141 was considered low-light, because it was isolated from the lower euphotic zone. These strains, or ecotypes, were later shown to live in different habitats (open-ocean or mesotrophic) and their distributions do not appear to be connected to light availability.[15] O. tauri was isolated from a coastal lagoon and appears to be light-polyvalent. Genetic data indicates that distinct molecular differences exist between the different ecotypes that have been detected.[16]

Prasinophytes are subject to infection by large double-stranded DNA viruses belonging to the genus Prasinovirus in the family Phycodnaviridae,[17][18][19] as well as a Reovirus.[20] It has been estimated that from 2 to 10% of the Micromonas pusilla population is lysed per day by viruses.[21]

Phylogeny

Recent studies agree that the prasinophytes are not a natural group, being highly paraphyletic.[3][22][23][24] Relationships among the groups making up the Chlorophyta are not fully resolved. The cladogram produced by Leliaert et al. 2011[3] and some modification according to Silar 2016,[25] Leliaert 2016[26] and Lopes dos Santos et al. 2017[27] is shown below. The blue shaded groups are or have traditionally been placed in the Prasinophyceae[2]). The species Mesostigma viride has been shown to be a member of the Streptophyta or basal Green algae. The others are member of the Chlorophyta.

Green Algae
Chlorophyta/
Palmophyllophyceae
 

Prasinococcales ("prasinophyte clade VI")

 
 

Palmophyllales

 
 
 
 
 

Pyramimonadophyceae ("prasinophyte clade I")

 
Mamiellophyceae
 

Monomastigales

 
 
 

Dolichomastigales

 
 

Mamiellales

 
 
("prasinophyte clade II")
 
 
Nephroselmidophyceae

Nephroselmidales ("prasinophyte clade III")

 
 
 

?Pycnococcaceae ("prasinophyte clade V")

 
 

Picocystophyceae ("prasinophyte clade VII C")

 
 
 

Chloropicophyceae ("prasinophyte clade VII A/B")

 
Tetraphytina
 

Pedinophyceae

 
Chlorophytina
 

Chlorodendrophyceae ("prasinophyte clade IV")

 
 
 

Trebouxiophyceae

 
 
 

Ulvophyceae

 
 

Chlorophyceae

 
 
 
 
 
 
 
 
 
Prasinophyta
Streptophyta
 
 

Chlorokybophyceae

 
 

Mesostigmatophyceae

 
 
 
 

Klebsormidiophyceae

 
 
 

Charophyceae

 
 
 

Zygnematophyceae

 
 

Coleochaetophyceae

 
 

Land plants

 
 
 
 
 
 

References

  1. ↑ "Class: Prasinophyceae taxonomy browser". AlgaeBase version 4.2 Worldwide electronic publication, National University of Ireland, Galway. 2007. http://www.algaebase.org/browse/taxonomy/?id=4345. 
  2. ↑ 2.0 2.1 2.2 Sym, S. D. and Pienaar, R. N. 1993. The class Prasinophyceae. In Round, F. E. and Chapman, D. J. (eds) Progress in Phycological Research, Vol. 9. Biopress Ltd., Bristol, pp. 281-376.
  3. ↑ 3.0 3.1 3.2 3.3 "Into the deep: new discoveries at the base of the green plant phylogeny". BioEssays 33 (9): 683–92. September 2011. doi:10.1002/bies.201100035. PMID 21744372. 
  4. ↑ "Smallest eukaryotic organism". Nature 370 (6487): 255. 1994. doi:10.1038/370255a0. Bibcode: 1994Natur.370..255C. 
  5. ↑ "Genome analysis of the smallest free-living eukaryote Ostreococcus tauri unveils many unique features". Proceedings of the National Academy of Sciences of the United States of America 103 (31): 11647–52. August 2006. doi:10.1073/pnas.0604795103. PMID 16868079. Bibcode: 2006PNAS..10311647D. 
  6. ↑ "The tiny eukaryote Ostreococcus provides genomic insights into the paradox of plankton speciation". Proceedings of the National Academy of Sciences of the United States of America 104 (18): 7705–10. May 2007. doi:10.1073/pnas.0611046104. PMID 17460045. Bibcode: 2007PNAS..104.7705P. 
  7. ↑ "Green evolution and dynamic adaptations revealed by genomes of the marine picoeukaryotes Micromonas". Science 324 (5924): 268–72. April 2009. doi:10.1126/science.1167222. PMID 19359590. Bibcode: 2009Sci...324..268W. https://semanticscholar.org/paper/8a80cd3476606d1895540024d12c80ea13c60524. 
  8. ↑ Mixotrophy in the Antarctic phytoflagellate, Pyramimonas gelidicola (Chlorophyta: Prasinophyceae)
  9. ↑ "Evolution of DDB1-binding WD40 (DWD) in the viridiplantae". PLOS ONE 13 (1): e0190282. 2018-01-02. doi:10.1371/journal.pone.0190282. PMID 29293590. Bibcode: 2018PLoSO..1390282T. 
  10. ↑ "The phycocyanobilin chromophore of streptophyte algal phytochromes is synthesized by HY2". The New Phytologist 214 (3): 1145–1157. May 2017. doi:10.1111/nph.14422. PMID 28106912. 
  11. ↑ "Vertical Structure of the Phytoplankton Community Associated with a Coastal Plume in the Gulf of Mexico". Marine Ecology Progress Series 251: 87–101. 2003. doi:10.3354/meps251087. Bibcode: 2003MEPS..251...87W. 
  12. ↑ "Diversity of picoplanktonic prasinophytes assessed by direct nuclear SSU rDNA sequencing of environmental samples and novel isolates retrieved from oceanic and coastal marine ecosystems". Protist 155 (2): 193–214. June 2004. doi:10.1078/143446104774199592. PMID 15305796. https://semanticscholar.org/paper/5f810fdbafdbc09476783f53a2f2b0dbf462ccc0. 
  13. ↑ "Assessing the dynamics and ecology of marine picophytoplankton: The importance of the eukaryotic component". Limnology and Oceanography 49 (1): 168–179. 2004. doi:10.4319/lo.2004.49.1.0168. Bibcode: 2004LimOc..49..168W. 
  14. ↑ "Picoeukaryote diversity in coastal waters of the Pacific Ocean". Aquatic Microbial Ecology 43 (2): 165–175. 2006. doi:10.3354/ame043165. http://oceanrep.geomar.de/46057/1/Picoeukaryote-diversity-in-coastal-waters-of-the-Pacific-OceanAquatic-Microbial-Ecology.pdf. 
  15. ↑ "Global distribution patterns of distinct clades of the photosynthetic picoeukaryote Ostreococcus". The ISME Journal 5 (7): 1095–107. July 2011. doi:10.1038/ismej.2010.209. PMID 21289652. 
  16. ↑ "Ecotype diversity in the marine picoeukaryote Ostreococcus (Chlorophyta, Prasinophyceae)". Environmental Microbiology 7 (6): 853–9. June 2005. doi:10.1111/j.1462-2920.2005.00758.x. PMID 15892704. 
  17. ↑ "A virus which lyses the marine nanoflagellate, "Micromonas pusilla"". Nature 281 (5729): 299–301. 1979. doi:10.1038/281299a0. Bibcode: 1979Natur.281..299M. 
  18. ↑ Cottrell, Matthew T.; Suttle, Curtis A. (1991). "Wide-spread occurrence and clonal variation in viruses which cause lysis of a cosmopolitan, eukaryotic marine phytoplankter, "Micromonas pusilla"". Marine Ecology Progress Series 78: 1–9. doi:10.3354/meps078001. Bibcode: 1991MEPS...78....1C. 
  19. ↑ "Abundance, spatial distribution and genetic diversity of Ostreococcus tauri viruses in two different environments". Environmental Microbiology Reports 2 (2): 313–21. April 2010. doi:10.1111/j.1758-2229.2010.00138.x. PMID 23766083. 
  20. ↑ "Micromonas pusilla reovirus: a new member of the family Reoviridae assigned to a novel proposed genus (Mimoreovirus)". The Journal of General Virology 87 (Pt 5): 1375–83. May 2006. doi:10.1099/vir.0.81584-0. PMID 16603541. 
  21. ↑ Cottrell, Matthew T.; Suttle, Curtis A. (1995-06-01). "Dynamics of lytic virus infecting the photosynthetic marine picoflagellate "Micromonas pusilla"". Limnology and Oceanography 40 (4): 730–739. doi:10.4319/lo.1995.40.4.0730. ISSN 1939-5590. Bibcode: 1995LimOc..40..730C. 
  22. ↑ "Green algae and the origin of land plants". American Journal of Botany 91 (10): 1535–56. October 2004. doi:10.3732/ajb.91.10.1535. PMID 21652308. 
  23. ↑ "Streptophyte algae and the origin of embryophytes". Annals of Botany 103 (7): 999–1004. May 2009. doi:10.1093/aob/mcp044. PMID 19273476. 
  24. ↑ "Nested in the Chlorellales or independent class? Phylogeny and classification of the Pedinophyceae (Viridiplantae) revealed by molecular phylogenetic analyses of complete nuclear and plastid-encoded rRNA operons". Protist 163 (5): 778–805. September 2012. doi:10.1016/j.protis.2011.11.004. PMID 22192529. 
  25. ↑ Silar, Philippe (2016), "Protistes Eucaryotes: Origine, Evolution et Biologie des Microbes Eucaryotes", HAL Archives-ouvertes: 1–462, https://hal.archives-ouvertes.fr/hal-01263138 
  26. ↑ "Chloroplast phylogenomic analyses reveal the deepest-branching lineage of the Chlorophyta, Palmophyllophyceae class. nov". Scientific Reports 6 (1): 25367. May 2016. doi:10.1038/srep25367. PMID 27157793. Bibcode: 2016NatSR...625367L. 
  27. ↑ "Chloropicophyceae, a new class of picophytoplanktonic prasinophytes". Scientific Reports 7 (1): 14019. October 2017. doi:10.1038/s41598-017-12412-5. PMID 29070840. Bibcode: 2017NatSR...714019L. 

External links

Wikidata ☰ Q134915 entry




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