Glomeromycota
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2008-06-23T22:26:47Z
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{{Taxobox
| name = Glomeromycota
| regnum = [[Fungus|Fungi]]
| phylum = [[Glomeromycota]]
| phylum_authority = C. Walker & A. Schuessler 2001<ref name=schuessler>{{cite journal | author = Schüßler, A. ''et al.'' |month=Dec| year=2001 | title=A new fungal phlyum, the ''Glomeromycota'': phylogeny and evolution. | journal=Mycol. Res. | volume=105 | issue=12 | pages=1413–1421 | url=http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=95091 | doi=10.1017/S0953756201005196}}</ref>
| classis = '''Glomeromycetes'''
| classis_authority = Caval.-Sm., 1998<ref>{{cite journal | author=[[Cavalier-Smith, T.]] | year = 1998 | title = A revised six-kingdom system of Life | journal = [[Biol. Rev. Camb. Philos. Soc.]] | volume = 73 | pages = 246}} (as "Glomomycetes")</ref>
| subdivision_ranks = Orders
| subdivision =
[[Glomerales]]<br/>
[[Diversisporales]]<br/>
[[Paraglomerales]]<br/>
[[Archaeosporales]]
}}
'''Glomeromycota''' (informally '''glomeromycetes''') is one of seven currently recognized phyla within the [[Kingdom (biology)|kingdom]] [[Fungi]]<ref name=Hibbett>
{{cite journal
| author=Hibbett, D.S., ''et al.''
| month=Mar
| year=2007
| title=A higher level phylogenetic classification of the ''Fungi''
| journal=Mycol. Res.
| volume=111
| issue=5
| pages=509–547
| doi=10.1016/j.mycres.2007.03.004}}
</ref>, with approximately 200 described species.<ref>[http://www.lrz-muenchen.de/~schuessler/amphylo/amphylogeny.html Neue Seite 1<!-- Bot generated title -->]</ref> Members of the Glomeromycota form [[arbuscular mycorrhiza]]s with the roots or thalli (e.g. in [[bryophyte]]s) of [[land plant]]s. ''Geosiphon pyriformis'' forms an endocytobiotic association with ''[[Nostoc]]'' [[cyanobacterium|cyanobacteria]]<ref>[http://www.lrz-muenchen.de/~schuessler/geosiphon/geosiphon.html New Page 1<!-- Bot generated title -->]</ref>. AM formation has not yet been shown for all species. The majority of evidence shows that the Glomeromycota are obligate [[biotroph]]s, dependent on symbiosis with land plants (''Nostoc'' in the case of ''Geosiphon'') for carbon and energy, but there is recent circumstantial evidence that some species may be able to lead an independent existence<ref>
{{cite journal
|author=Hempel, S., Renker, C. & Buscot, F.
|year=2007
|title=Differences in the species composition of arbuscular mycorrhizal fungi in spore, root and soil communities in a grassland ecosystem
|journal=Environmental Microbiology
|volume=9
|issue=8
|pages=1930–1938
|doi=10.1111/j.1462-2920.2007.01309.x}}
</ref>. The [[arbuscular mycorrhiza]]l species are terrestrial and widely distributed in soils worldwide where they form symbioses with the roots of the majority of plant species. They can also be found in wetlands, including salt-marshes, and associated with epiphytic plants.
== Reproduction ==
The Glomeromycota have generally [[coenocyte|coenocytic]] (occasionally sparsely [[septum|septate]]) [[mycelia]] and reproduce asexually through blastic development of the hyphal tip to produce [[spore]]s<ref name=schuessler/> (Glomerospores) with diameters of 80-500μm<ref name=simon/>. In some, complex spores form within a terminal saccule.<ref name=schuessler/>
== Phylogeny ==
Initial studies of the Glomeromycota were based on the morphology of soil-borne sporocarps (spore clusters) found in or near colonized plant roots.<ref>
{{cite journal
| author=Tulasne, L.R., & C. Tulasne
| year=1844
| title=Fungi nonnulli hipogaei, novi v. minus cogniti auct | journal=Giornale Botanico Italiano
| volume=2
| pages=55–63}}
</ref> Distinguishing features such as wall morphologies, size, shape, color, [[hypha]]l attachment and reaction to staining compounds allowed a phylogeny to be constructed.<ref name=wright>Wright, S.F. Management of Arbuscular Mycorrhizal Fungi. 2005. In Roots and Soil Management: Interactions between roots and the soil. Ed. Zobel, R.W., Wright, S.F. USA: American Society of Agronomy. Pp 183-197.</ref> Superficial similarities led to the initial placement of genus ''Glomus'' in the unrelated family [[Endogonaceae]].<ref>
{{cite journal
|author=Thaxter, R.
|year=1922
|title=A revision of the Endogonaceae
|journal=Proc. Am. Acad. Arts Sci.
|volume=57
|pages=291–341}}
</ref> Following broader reviews that cleared up the sporocarp confusion, the Glomeromycota were first proposed in the genera ''Acaulospora'' and ''Gigaspora''<ref>
{{cite journal
|author=J.W. Gerdemann & J.M. Trappe
|year=1974
|title=The Endogonaceae in the Pacific Northwest
|journal=Mycologia Memoirs
|volume=5
|pages=1–76}}
</ref> before being accorded their own order with the three [[family (biology)|families]] Glomaceae (now [[Glomeraceae]]), Acaulosporaceae and Gigasporaceae.<ref>{{cite journal
|author=J.B. Morton & G.L. Benny
|year=1990
|url=http://www.cybertruffle.org.uk/cyberliber/59575/0037/0471.htm
|title=Revised classification of arbuscular mycorrhizal fungi (Zygomycetes): a new order, Glomales, two new suborders, Glomineae and Gigasporineae, and two new families, Acaulosporaceae and Gigasporaceae, with an emendation of Glomaceae
|journal=Mycotaxon
|volume=37
|pages=471–491}}
</ref>
With the advent of molecular techniques this classification has undergone major revision. An analysis of small subunit (SSU) [[rRNA]] sequences<ref>
{{cite journal
| author = Schüßler, A. ''et al.''
| month=Jan
| year=2001
| title=Analysis of partial Glomales SSU rRNA gene sequences: implications for primer design and phylogeny
| journal=Mycol. Res.
| volume=105
| issue=1
| pages=5–15
| doi=10.1017/S0953756200003725}}
</ref> indicated that they share a common ancestor with the [[Dikarya]] <ref name=schuessler/>.
Several species which produce glomoid spores (i.e. spores similar to ''[[Glomus]]'') in fact belong to other deeply divergent lineages<ref>{{cite journal|author=Redeker, D.|year= 2002|title= Molecular identification and phylogeny of arbuscular mycorrhizal fungi|journal= Plant and Soil|volume= 244|pages=67–73|doi= 10.1023/A:1020283832275}}</ref> and were placed in the orders, [[Paraglomerales]] and [[Archaeosporales]].<ref name=schuessler/> This new classification includes the [[Geosiphonaceae]], which presently contains one fungus (''Geosiphon pyriformis'') that forms endosymbiotic associations with the cyanobacterium ''Nostoc punctiforme''<ref name=schuessler2>{{cite journal|author=Schüßler, A.|year= 2002|title= Molecular phylogeny, taxonomy, and evolution of ''Geosiphon pyriformis'' and arbuscular mycorrhizal fungi|journal= Plant and Soil|volume= 224 |pages=75–83|doi= 10.1023/A:1020238728910}}</ref> and produces spores typical to this phylum, in the [[Archaeosporales]].
Work in this field is incomplete, and members of ''Glomus'' may be better suited to different genera<ref>
{{cite journal
| author = Walker, C.
| year = 1992
| title = Systematics and taxonomy of the arbuscular mycorrhizal fungi (Glomales) - a possible way forward
| journal = Agronomie
| volume = 12
| pages = 887–897
| doi = 10.1051/agro:19921026}}
</ref> or families.<ref name=simon>
{{cite journal
|author=Simon, L., Bousquet, J., Levesque, C., Lalonde, M.
|year= 1993
|title= Origin and diversification of endomycorrhizal fungi and coincidence with vascular land plants
|journal= [[Nature (journal)|Nature]]
|volume= 363
|issue=6424
|pages= 67–69
|doi= 10.1038/363067a0}}
</ref>
== Molecular biology ==
The biochemical and genetic characterization of the Glomeromycota has been hindered by their [[biotrophic]] nature, which impedes laboratory culturing. This obstacle was eventually surpassed with the use of root cultures. The first mycorrhizal gene to be sequenced was the small-subunit [[ribosomal RNA]] (SSU rRNA).<ref>
{{cite journal
|author=Simon, L. Lalonde, M. Bruns, T.D.
|year= 1992
|title= Specific Amplification of 18S Fungal Ribosomal Genes from Vesicular-Arbuscular Endomycorrhizal Fungi Colonizing Roots
|journal= American Society of Microbiology
|volume= 58
|pages= 291–295}}
</ref> This gene is highly conserved and commonly used in [[phylogenetics|phylogenetic]] studies so was isolated from [[spore]]s of each [[Taxonomy|taxonomic]] group before amplification through the [[polymerase chain reaction]] (PCR). A [[molecular clock]] approach, based on the substitution rates of SSU sequences, was used to estimate the time of divergence of the fungi. The molecular analysis found that they are between 462 and 353 Million years old.<ref name=simon/> The data enforces the long-held theory that they were instrumental in the colonization of land by plants.<ref>{{cite journal
|author=D.W. Malloch, K.A. Pirozynski & P.H. Raven
|year=1980
|title=Ecological and evolutionary significance of mycorrhizal symbiosis in vascular plants (a review)
|journal=[[Proc. Natl Acad. Sci. USA]]
|volume=77
|issue=4
|pages=2113–2118
|url=http://www.pnas.org/cgi/content/short/77/4/2113
|doi=10.1073/pnas.77.4.2113
|pmid=16592806}}
</ref>
== See also ==
{{wikispecies}}
== References ==
{{reflist}}
== External links ==
*[http://tolweb.org/Glomeromycota/28715 Tree of Life Glomeromycota]
*[http://invam.caf.wvu.edu/fungi/taxonomy/glomales.htm Glomeromycota] at the International Culture Collection of VA [[Mycorrhiza|Mycorrhizal Fungi]] (INVAM)
*[http://bugs.bio.usyd.edu.au/Mycology/Taxonomy/glomeromycota.shtml Glomeromycota] at the [[University of Sydney]] [[Fungal]] [[Biology]] s|ite
*[http://amf-phylogeny.com 'AMF-phylogeny'] - 'Glomeromycota database' web-site at the University of Munich
[[Category:Fungi]]
[[Category:Glomeromycota| ]]
[[Category:Soil biology]]
[[cs:Glomeromycota]]
[[de:Arbuskuläre Mykorrhizapilze]]
[[es:Glomeromycota]]
[[eu:Glomeromycota]]
[[fr:Glomeromycota]]
[[hu:Endomikorrhiza-gombák]]
[[pl:Grzyby mikoryzowe]]
[[pt:Glomeromycota]]
[[ro:Glomeromycota]]