Myco-heterotrophy 5224295 222977988 2008-07-02T00:32:28Z Rkitko 536375 no need to bold terms in section [[Image:Monotropastrum humile.jpg|thumb|225px|right|''Monotropastrum humile'', an obligate myco-heterotroph.]] '''Myco-heterotrophy''' is a [[symbiotic]] relationship between certain kinds of [[plants]] and [[fungi]], in which the plant gets all or part of its food from [[parasitism]] upon fungi rather than from [[photosynthesis]]. A '''myco-heterotroph''' is the [[parasitic plant]] partner in this relationship. Myco-heterotrophy is considered a kind of [[Cheating (biology)|cheating]] relationship and myco-heterotrophs are sometimes informally referred to as "'''mycorrhizal cheaters'''". This relationship is sometimes referred to as '''mycotrophy''', though this term is also used for plants that engage in [[mutualistic]] [[mycorrhizal]] relationships. ==Relationship between myco-heterotrophs and host fungi== [[Image:Uniflora-root.jpg|frame|right|Myco-heterotrophic roots of ''[[Monotropa uniflora]]'' with ''[[Russula]] brevipes'' [[mycelium]].]] Full (or obligate) myco-heterotrophy exists when a non-photosynthetic plant (a plant largely lacking in [[chlorophyll]] or otherwise lacking a functional [[photosystem]]) gets all of its food from the fungi that it parasitizes. Partial (or facultative) myco-heterotrophy exists when a plant is capable of photosynthesis, but parasitizes fungi as a supplementary food supply. There are also plants, such as some [[orchid]] species, that are non-photosynthetic and obligately myco-heterotrophic for part of their [[biological life cycle|life cycle]], and photosynthetic and facultatively myco-heterotrophic or non-myco-heterotrophic for the rest of their life cycle.<ref name="leake94">Leake JR. 1994. [http://www.blackwell-synergy.com/javascript:newWindow/doi/pdf/10.1111/j.1469-8137.1994.tb04272.x The biology of myco-heterotrophic ('saprophytic') plants.] ''New Phytologist'' 127: 171–216. ''Warning: large document''</ref> (Not all non-photosynthetic or "[[Wiktionary:achlorophyllous|achlorophyllous]]" plants are myco-heterotrophic – some non-photosynthetic plants like [[Cuscuta|dodder]] directly parasitize the [[vascular tissue]] of other plants.<ref name="dawson">Dawson JH, Musselman LJ, Wolswinkel P, Dörr I. 1994. Biology and control of ''Cuscuta''. ''Reviews of Weed Science'' 6: 265–317.</ref>) In the past, non-photosynthetic plants were mistakenly thought to get food by breaking down [[organic matter]] in a manner similar to [[saprotrophic]] fungi. Such plants were therefore called "[[saprophytes]]". It is now known that no plant is physiologically capable of direct breakdown of organic matter and that in order to get food, non-photosynthetic plants must engage in parasitism, either through myco-heterotrophy or direct parasitism of other plants.<ref name="bid05">Bidartondo MI. 2005. [http://www.bio.ic.ac.uk/research/bidartondo/pubs/Bidartondo2005.pdf The evolutionary ecology of myco-heterotrophy.] ''New Phytologist'' 167: 335–352.</ref> <ref name="leake05">Leake JR. 2005. Plants parasitic on fungi: unearthing the fungi in myco-heterotrophs and debunking the ‘saprophytic’ plant myth. ''Mycologist'' 19: 113–122. ([http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=340905&fulltextType=RA&fileId=S0269915X05003046 abstract])). </ref> The interface between the plant and fungal partners in this association is between the roots of the plant and the mycelium of the fungus. Myco-heterotrophy therefore closely resembles [[mycorrhiza]] (and indeed is thought to have evolved from mycorrhiza), <ref name="bid05"> </ref> except that in myco-heterotrophy, the flow of carbon is from the fungus to the plant, rather than vice versa.<ref name="trud03">Trudell SA, Rygiewicz PT, Edmonds RL. 2003. [http://www.esf.edu/EFB/horton/Trudell%20et%20al2003.pdf Nitrogen and carbon stable isotope abundances support the myco-heterotrophic nature and host-specificity of certain achlorophyllous plants.] ''New Phytologist'' 160: 391–401.</ref> <ref name="bid04">Bidartondo MI, Burghardt B, Gebauer G, Bruns TD, Read DJ. 2004. [http://www.bio.ic.ac.uk/research/bidartondo/pubs/PRSB2004.pdf Changing partners in the dark: isotopic and molecular evidence of ectomycorrhizal liaisons between forest orchids and trees.] ''Proceedings of the [[Royal Society of London]]'', series B 271: 1799–1806.</ref> Myco-heterotrophs can therefore be seen as ultimately being [[epiparasites]], since they take energy from fungi that in turn get their energy from [[vascular plants]].<ref name="bid05"> </ref> <ref name="leake05"> </ref> Indeed, much myco-heterotrophy takes place in the context of a [http://www.mykoweb.com/articles/MycorrhizalNetworks.html common mycorrhizal network], in which plants use mycorrhizal fungi to exchange carbon and nutrients with other plants. <ref name="leake05"> </ref> In these systems, myco-heterotrophs play the role of "mycorrhizal cheaters", taking carbon from the common network, but giving nothing in return.<ref name="bid05"> </ref> ==Species diversity of myco-heterotrophs and host fungi== Myco-heterotrophs are found among a number of plant groups. All [[monotropes]] and non-photosynthetic [[orchids]] are full myco-heterotrophs, as is the non-photosynthetic [[Marchantiophyta|liverwort]] ''Cryptothallus''. Partial myco-heterotrophy is common in the [[Gentian family]], in photosynthetic orchids, and a number of other plant groups. Some [[fern]]s and [[clubmosses]] have myco-heterotrophic [[gametophyte]] stages.<ref name="leake94"> </ref> <ref name="leake05"> </ref> <ref name="taylor02">Taylor DL, Bruns TD, Leake JR, Read DJ. 2002. [http://mercury.bio.uaf.edu/~lee_taylor/Design/Assets/pdfs/Taylor_ES157Chap15.pdf Mycorrhizal specificity and function in myco-heterotrophic plants.] In: ''The Ecology of Mycorrhizas'' (Sanders IR, van der Heijden M, eds.), Ecological Studies vol. 157, pp 375–414. Berlin: Springer-Verlag. (NOTE: this PDF is from the page proofs, and is not identical to the published version)</ref> The fungi that are parasitized by myco-heterotrophs are typically fungi with large energy reserves to draw on, usually mycorrhizal fungi, though there is some evidence that they may also parasitize parasitic fungi that form extensive mycelial networks, such as ''[[Armillaria]]''.<ref name="leake05"> </ref> ==References== <div class="references-small"><references/></div> ==Further reading== * Hershey DR. 1999. Myco-heterophytes and parasitic plants in food chains. ''American Biology Teacher'' 61: 575–578. * Hibbett DS. 2002. [http://plantbio.berkeley.edu/~bruns/ftp/hibbett2002.pdf When good relationships go bad.] ''[[Nature (journal)|Nature]]'' 419: 345–346. * Werner PG. 2006. [http://www.mssf.org/mnews/0603mn.pdf Myco-heterotrophs: hacking the mycorrhizal network.] ''Mycena News'' 57(3): 1,8. * [http://www.bio.ic.ac.uk/research/bidartondo/ Dr. Martin Bidartondo: Selected publications] * [http://users.iab.uaf.edu/~lee_taylor/HTML_Pages/Publications.htm D. Lee Taylor Lab: Recent Publications] ==External links== * [http://www.parasiticplants.siu.edu/Mycotrophs/Mycotrophs.html The Strange and Wonderful Myco-heterotrophs] ''The Parasitic Plant Connection'', [[Southern_Illinois_University_Carbondale|SIU Carbondale]], College of Science. * [http://waynesword.palomar.edu/pljune97.htm ''Wayne's Word'' Noteworthy Plant For June 1997: Fungus Flowers – Flowering Plants that Resemble Fungi] by WP Armstrong. * [http://botit.botany.wisc.edu/toms_fungi/may2003.html Fungus of the Month for October 2002: ''Monotropa uniflora''] by Tom Volk, ''TomVolkFungi.net'' * [http://plantbio.berkeley.edu/%7Ebruns/tour/monotrope.html Martín's Treasure Chest] – images of myco-heterotrophs by mycologist Martín Bidartondo. [[Category:Botany]] [[Category:Ecology]] [[Category:Mycology]] [[Category:Parasitic plants|*]] [[Category:Parasites]] [[Category:Symbiosis]] [[el:Σαπρόφυτα]] [[es:Micoheterotrofía]]