Myco-heterotrophy

This is a good article. Click here for more information.
Source: Wikipedia, the free encyclopedia.
Monotropa uniflora, an obligate myco-heterotroph known to parasitize fungi belonging to the Russulaceae.[1]

Myco-heterotrophy (from

mycorrhizal
relationships.

Relationship between myco-heterotrophs and host fungi

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 life cycle, and photosynthetic and facultatively myco-heterotrophic or non-myco-heterotrophic for the rest of their life cycle.[2] Not all non-photosynthetic or "achlorophyllous" plants are myco-heterotrophic – some non-photosynthetic plants like dodder directly parasitize the vascular tissue of other plants.[3] The partial or full loss of photosynthesis is reflected by extreme physical and functional reductions of plastid genomes in mycoheterophic plants,[4] an ongoing evolutionary process.[5]

In the past, non-photosynthetic plants were mistakenly thought to get food by breaking down

saprophytes". It is now known that these plants are not physiologically capable of directly breaking down 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.[6][7]

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),[6] except that in myco-heterotrophy, the flow of carbon is from the fungus to the plant, rather than vice versa.[8][9]

Most myco-heterotrophs can therefore be seen as ultimately being

vascular plants.[6][7][10] Indeed, much myco-heterotrophy takes place in the context of common mycorrhizal networks,[11] in which plants use mycorrhizal fungi to exchange carbon and nutrients with other plants.[7] In these systems, myco-heterotrophs play the role of "mycorrhizal cheaters", taking carbon from the common network, with no known reward.[6] A special form of mycoheterotrophic association, which appears to be a chimera between the haustorial parasitism of a parasitic plant and mycoheterotrophy, is observed in Parasitaxus usta, the only mycoheterotrophic gymnosperm.[12]

In congruence with older reports, it has been recently shown that some myco-heterotrophic orchids can be supported by saprotrophic fungi, exploiting litter- or wood-decaying fungi.[13] In addition, several green plants (evolutionarily close to myco-heterotrophic species) have been shown to engage in partial myco-heterotrophy, that is, they are able to take carbon from mycorrhizal fungi, in addition to their photosynthetic intake.[14][15]

Species diversity of myco-heterotrophs and host fungi

See also: List of myco-heterotrophic genera

Myco-heterotrophs are found among several plant groups, mainly

clubmosses have myco-heterotrophic gametophyte stages.[2][7][17] 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.[7]
Examples of fungi parasitized by myco-heterotrophic plants can be found among the
orchid mycorrhizal fungi.[18] The great diversity in unrelated plant families with myco-heterotrophic members, as well as the diversity of fungi targeted by myco-heterotrophs, suggests multiple parallel evolutions of myco-heterotrophs from mycorrhizal ancestors.[18]

References

  1. PMID 17139846
    .
  2. ^
    S2CID 85142620
    .
  3. ^ Dawson, JH; Musselman, LJ; Wolswinkel, P; Dörr, I (1994). "Biology and control of Cuscuta". Reviews of Weed Science. 6: 265–317.
  4. doi:10.1016/bs.abr.2017.11.014
    .
  5. PMID 29502351
    .
  6. ^
    PMID 15998389
    .
  7. ^
    doi:10.1017/S0269915X05003046
    .
  8. PMID 33832180
    .
  9. PMID 15315895. Archived from the original
    (PDF) on 2011-03-31. Retrieved 2020-08-19.
  10. S2CID 17479936
    .
  11. ^ Peter Kennedy (November 2005). "Common Mycorrhizal Networks: An Important Ecological Phenomenon". MykoWeb (originally published on Mycena News). Retrieved January 19, 2012.
  12. doi:10.1111/j.1365-3040.2005.01378.x
    .
  13. PMID 19694964
    .
  14. PMID 33873535
    .
  15. PMID 19162524
    .
  16. doi:10.1111/j.1095-8339.2007.00743.x
    . Retrieved 23 October 2023.
  17. ISBN 3-540-00204-9
    . (NOTE: this PDF is from the page proofs, and is not identical to the published version)
  18. ^
    S2CID 85629763
    .

Further reading

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Myco-heterotrophy&oldid=1184166917"