Charophyta

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For an explanation of very similar terms, see Streptophyta.
Charophyta
Scientific classificationEdit this classification
(unranked): Viridiplantae
(unranked): Charophyta
Migula 1897,[1] sensu Leliaert et al. 2012
Groups included
Cladistically included but traditionally excluded taxa

Embryophyta

Charophyta (

Embryophyta emerged deep within Charophyta, possibly from terrestrial unicellular charophytes,[4] with the class Zygnematophyceae as a sister group.[5][6][7][8][9]

With the Embryophyta now

oogonia
.

The name comes from the genus Chara, but the finding that the Embryophyta actually emerged in them has not resulted in a much more restricted meaning of the Charophyta, namely to a much smaller side branch. This more restricted group corresponds to the Charophyceae.

Description

The Zygnematophyceae formerly known as the, Conjugatophyceae, generally possess two fairly elaborate chloroplasts in each cell, rather than many discoid ones. They reproduce asexually by the development of a septum between the two cell-halves or semi-cells (in unicellular forms, each daughter-cell develops the other semi-cell afresh) and sexually by conjugation, or the fusion of the entire cell-contents of the two conjugating cells. The saccoderm desmids and the placoderm or true desmids, unicellular or filamentous members of the Zygnematophyceae, are dominant in non-calcareous, acid waters of oligotrophic or primitive lakes (e.g. Wastwater), or in lochans, tarns and bogs, as in the West of Scotland, Eire, parts of Wales and of the Lake District.[16]

Klebsormidiophyceae, is a simple filamentous form with circular, plate-like chloroplasts, reproducing by fragmentation, by dorsiventral, biciliate swarmers and, according to Wille, a twentieth-century algologist, by aplanospores.[17] Sexual reproduction is simple and isogamous (the male and female gametes are outwardly indistinguishable).[17]

The Charales (Charophyceae), or stoneworts, are freshwater and brackish algae with slender green or grey stems; the grey colour of many species results from the deposition of lime on the walls, masking the green colour of the chlorophyll. The main stems are slender and branch occasionally. Lateral branchlets occur in whorls at regular intervals up the stem, they are attached by rhizoids to the substrate.[18] The reproductive organs consist of antheridia and oogonia, though the structures of these organs differ considerably from the corresponding organs in other algae. As a result of fertilization, a protonema is formed, from which the sexually reproducing algae develops.

A new terrestrial genus found in sandy soil in the Czech Republic, Streptofilum, may belong in its own class due its unique phylogenetic position. A cell wall is absent, instead the cell membrane consists of many layers of specific scales. It is a short, filamentous and unbranched algae surrounded by a mucilaginous sheath, which often disintegrates to diads and unicells.[19]

Reproduction

The cells in Charophyta algae are all

haploid, except during sexual reproduction, where a diploid unicellular zygote is produced. The zygote becomes four new haploid cells through meiosis, which will develop into new algae. In multicellular forms these haploid cells will grow into a gametophyte. In embryophytes (land plants) the zygote will instead give rise to a multicellular sporophyte.[20][21]

Classification

Charophyta are complex green algae that form a sister group to the

aldolase, Cu/Zn superoxide dismutase, glycolate oxidase, flagellar peroxidase), lateral flagella (when present), and, in many species, the use of phragmoplasts in mitosis.[22] Thus Charophyta and Embryophyta together form the clade Streptophyta
, excluding the Chlorophyta.

Charophytes such as Palaeonitella cranii and possibly the yet unassigned Parka decipiens[23] are present in the fossil record of the Devonian.[15] Palaeonitella differed little from some present-day stoneworts.

Cladogram

There is an emerging consensus on green algal relationships, mainly based on molecular data.[22][24][25][26][10][2][6][27][28][29][30][31][19][32] The Mesostigmatophyceae (including Spirotaenia, and Chlorokybophyceae) are at the base of charophytes (streptophytes). The cladograms below show consensus phylogenetic relationships based on plastid genomes[33] and a new proposal for a third phylum of green plants based on analysis of nuclear genomes.[34]

Consensus plastid phylogeny
Viridiplantae
Consensus relationships among major green algal lineages inferred in recent plastid phylogenomic studies[33]
Prasinodermophyta hypothesis
Viridiplantae/
green algae
Relationships among major green algal lineages based on a recent nuclear phylogenomic study[34]

Mesostigmatophyceae s.l. in the cladograms corresponds to a clade of a narrower circumscription, Mesostigmatophyceae s.s., and a separate class Chlorokybophyceae, as used by AlgaeBase.[1]

The Mesostigmatophyceae are not filamentous, but the other basal charophytes (streptophytes) are.[35][19][29]

References

  1. ^ a b Guiry, M.D.; Guiry, G.M. "Charophytes". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Retrieved 2022-02-21.
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    PMID 21652308
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  3. PMID 25923521
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  4. PMID 29318635
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  5. PMID 29851097
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  6. ^
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  7. PMID 25355905
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  8. PMID 26895731
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  9. ^ Treatise on invertebrate paleontology. Part B. Protoctista 1. Volume1: Charophyta.[1]
  10. ^
    ISBN 9783319281476
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  11. PMID 21640897
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  12. S2CID 35983109
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  13. PMID 21652308
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  14. S2CID 9864200
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  15. ^
    S2CID 128869547
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  16. ^ West, G.S; Fritsch, F.E. (1927). A Treatise of the British Freshwater Algae. Cambridge: Cambridge University Press.
  17. ^ a b Fritsch, F.E. (1935). The Structure and Reproduction of the Algae, vol I. Cambridge University Press. pp. 205–206.
  18. ISBN 9781904890317
  19. ^
    PMID 29860113
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  20. ^ Evolution and development of land plant embryos - GtR - UKRI
  21. PMID 19273476
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  22. ^
    S2CID 17603352. Archived from the original
    (PDF) on 2015-06-26. Retrieved 2016-10-04.
  23. doi:10.1093/oxfordjournals.aob.a087852
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  24. PMID 22192529
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  25. PMID 22877776
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  26. PMID 27157793
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  27. PMID 23020233
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  28. PMID 17222354
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  29. ^
    PMID 25324214
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  30. PMID 28808007
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  31. PMID 29603143
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  32. ^ Glass, Sarah (2021). Chloroplast Genome Evolution in the Klebsormidiophyceae and Streptofilum (MS thesis). Lehman College.
  33. ^
    ISBN 9780128134573
  34. ^
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  35. PMID 30007417
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External links
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