Editing Zygnematales

{{Short description|Order of algae}}
{{Automatic taxobox
| image = Spirogyra-bgiu.jpg
| image_caption = ''[[Spirogyra]]'' green algae
| taxon = Zygnematales
| authority = C.E.Bessey, 1907
| synonyms_ref       = {{citation needed|date=February 2016}}
| subdivision_ranks  = Families
| subdivision        = *[[Zygnemataceae]]
*[[Mesotaeniaceae]]
}}

The '''Zygnematales''' ({{langx|el|ζυγός}} (''zygós'') and νῆμα (''nḗma'') ([[nominative|nom.]]), νήματος (''nḗmatos'') ([[genitive|gen.]])), also called the '''Conjugatales''',<ref>{{cite book|vauthors=Curtis CC|title=A Text-book of General Botany|year=1897|url=https://books.google.com/books?id=PllHAAAAYAAJ&pg=PA114|page=114–118|access-date=June 2, 2024|chapter=Order 3. Conjugatales}}</ref> are an [[order (biology)|order]] of [[green alga]]e,<ref name="pmid16236178">{{cite journal |vauthors=Turmel M, Otis C, Lemieux C |title=The complete chloroplast DNA sequences of the charophycean green algae Staurastrum and Zygnema reveal that the chloroplast genome underwent extensive changes during the evolution of the Zygnematales |journal=BMC Biol. |volume=3|pages=22 |year=2005 |pmid=16236178 |pmc=1277820 |doi=10.1186/1741-7007-3-22 |doi-access=free }}</ref> comprising several thousand different [[species]] in two families. The larger family Zygnemataceae, with well-known [[genus|genera]] such as ''Zygnema'' and ''[[Spirogyra]]'', includes members that grow as unbranched filaments, which grow longer through normal [[cell division]]. This group includes the [[desmids]]. Most members of both families live in [[freshwater]], and form an important component of the algal scum that grows on or near plants and rocks.

Systematically they fall within the division [[Charophyta]]/[[Streptophyta]], in which the land plants ([[Embryophyte|Embryophyta]]) emerged.<ref>{{Cite web|url=http://esciencenews.com/articles/2011/04/17/ancestors.land.plants.revealed|title = Ancestors of land plants revealed &#124; (E) Science News}}</ref>

[[Sexual reproduction]] in Zygnematales takes place through a process called ''[[Isogamy|conjugation]]''.<ref name="pmid17272304">{{cite journal |author=Kapraun DF |title=Nuclear DNA Content Estimates in Green Algal Lineages: Chlorophyta and Streptophyta |journal=Ann. Bot. |volume=99 |issue=4 |pages=677–701 |date=April 2007 |pmid=17272304 |doi=10.1093/aob/mcl294 |url= |pmc=2802934}}</ref> Here filaments of opposite gender line up, and tubes form between corresponding cells. The male cells then become amoeboid and crawl across, or sometimes both cells crawl into the tube. The cells then meet and fuse to form a [[zygote]], which later undergoes [[meiosis]] to produce new filaments. As in plants, only the female passes [[chloroplast]]s on to the offspring.<ref>{{cite journal|vauthors=Permann C, Píchrtová M, Šoljaková T, Herburger K, Jouneau PH, Uwizeye C, Falconet D, Marechai E, Holzinge A|title=3D-reconstructions of zygospores in ''Zygnema vaginatum'' (Charophyta) reveal details of cell wall formation, suggesting adaptations to extreme habitats|url=https://onlinelibrary.wiley.com/doi/epdf/10.1111/ppl.13988|journal=Physiologia Plantarum|pmid=37616005|doi=10.1111/ppl.13988|date=August 23, 2023|veditors=Pfeifer L|page=e13988|volume=175|issue=4|doi-access=free}}</ref>

Other conjugating algae are the [[Mesotaeniaceae]], sister of the Zygnematales, and ''[[Spirotaenia]]'', a basal green algae. Additionally, the [[Desmidiales]] appear to have emerged deep within the Zygnematales, and are also conjugating.<ref>{{Cite journal|last1=Lemieux|first1=Claude|last2=Otis|first2=Christian|last3=Turmel|first3=Monique|date=2016|title=Comparative Chloroplast Genome Analyses of Streptophyte Green Algae Uncover Major Structural Alterations in the Klebsormidiophyceae, Coleochaetophyceae and Zygnematophyceae|journal=Frontiers in Plant Science|language=en|volume=7|pages=697|doi=10.3389/fpls.2016.00697|pmid=27252715|issn=1664-462X|pmc=4877394|doi-access=free}}</ref>

==Gallery==
<gallery>
File:Netrium oblongum var. cylindricum.jpg|''[[Netrium]] oblongum''.&nbsp; A saccoderm "desmid"
File:Spirogyra cell.jpg|Single ''[[Spirogyra]]'' cell
File:20090328 2222 Spirogyra.jpg|''[[Spirogyra]]''.&nbsp; Each numbered tick = 122 μM
File:20090328 2225 Spirogyra.jpg|''[[Spirogyra]]''.&nbsp; Each numbered tick = 20 μM
File:SpirogyraConjugation100x.jpg|Microscopic view of ''[[Spirogyra]]'' conjugation
File:20090906 022641 Algae.jpg|''[[Zygnema]]''.&nbsp; Each numbered tick = 122 μM
File:20100417 005205 Zygnema.jpg|''[[Zygnema]]''.&nbsp; Each numbered tick = 20 μM
</gallery>

==References==
{{Reflist}}

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[[Category:Zygnematales| ]]
[[Category:Charophyta orders]]