Arbuscular mycorrhiza

Flax root cortical cells containing paired arbuscules
A fluorescent microscopy image of a fungal arbuscule stained with WGA and Alexa Fluor
Vesicular arbuscular mycorrhizae in the terminal roots of Horse Gram plant
Bilayered glomoid spore of arbuscular mycorrhizal fungi in the root of Horse Gram
Bilayered glomoid spore of arbuscular mycorrhizal fungi in the root of Horse Gram

An arbuscular mycorrhiza (AM) (plural mycorrhizae) is a type of mycorrhiza in which the symbiont fungus (AM fungi, or AMF) penetrates the cortical cells of the roots of a vascular plant forming arbuscules. Arbuscular mycorrhiza is a type of endomycorrhiza along with ericoid mycorrhiza and orchid mycorrhiza (not to be confused with ectomycorrhiza). They are characterized by the formation of unique tree-like structures, the arbuscules.[1] In addition, globular storage structures called vesicles are often encountered.

Arbuscular mycorrhizae are formed by fungi in the subphylum Glomeromycotina. This subphylum, along with the Mortierellomycotina, and Mucoromycotina, form the phylum Mucoromycota, a sister clade of the more well-known and diverse dikaryan fungi.[2]

AM fungi help plants to capture nutrients such as phosphorus, sulfur, nitrogen and micronutrients from the soil. It is believed that the development of the arbuscular mycorrhizal symbiosis played a crucial role in the initial colonisation of land by plants and in the evolution of the vascular plants.[3] It has been said that it is quicker to list the plants that do not form endomycorrhizae than those that do.[4] This symbiosis is a highly evolved mutualistic relationship found between fungi and plants, the most prevalent plant symbiosis known,[5] and AMF is found in 80% of vascular plant families in existence today.[6]

Previously this type of mycorrhizal associations were called 'Vesicular arbuscular mycorrhiza (VAM)', but since some members of these fungi do not produce any vesicles, such as the members of Gigasporaceae; the term has been changed to 'Arbuscular Mycorrhizae' to include them.[7][8]

Advances in research on mycorrhizal physiology and ecology since the 1970s have led to a greater understanding of the multiple roles of AMF in the ecosystem. An example is the important contribution of the glue-like protein glomalin to soil structure (see below). This knowledge is applicable to human endeavors of ecosystem management, ecosystem restoration, and agriculture.

  1. ^ Mycorrhizal Symbiosis. 2008. doi:10.1016/b978-0-12-370526-6.x5001-6. ISBN 978-0-12-370526-6.
  2. ^ Spatafora, Joseph W.; Chang, Ying; Benny, Gerald L.; Lazarus, Katy; Smith, Matthew E.; Berbee, Mary L.; Bonito, Gregory; Corradi, Nicolas; Grigoriev, Igor; Gryganskyi, Andrii; James, Timothy Y.; O'Donnell, Kerry; Roberson, Robert W.; Taylor, Thomas N.; Uehling, Jessie (2016). "A phylum-level phylogenetic classification of zygomycete fungi based on genome-scale data". Mycologia. 108 (5): 1028–1046. doi:10.3852/16-042. ISSN 0027-5514. PMC 6078412. PMID 27738200.
  3. ^ Brundrett, M.C. (2002). "Coevolution of roots and mycorrhizas of land plants". New Phytologist. 154 (2): 275–304. doi:10.1046/j.1469-8137.2002.00397.x. PMID 33873429.
  4. ^ Barbour, M.G.; Burk, J.H.; Pitts, W.D. (1980). Terrestrial plant ecology. Frontiers in Physics. Benjamin/Cummings Publishing Company. p. 118. ISBN 978-0-8053-0540-1.
  5. ^ Simon, L.; Bousquet, J.; Levesque, C.; Lalonde, M. (1993). "Origin and diversification of endomycorrhizal fungi and coincidence with vascular land plants". Nature. 363 (6424): 67–69. Bibcode:1993Natur.363...67S. doi:10.1038/363067a0. S2CID 4319766.
  6. ^ Schüßler, A.; et al. (2001). "A new fungal phylum, the Glomeromycota: phylogeny and evolution". Mycol. Res. 105 (12): 1413–1421. doi:10.1017/S0953756201005196.
  7. ^ Moore, David; Robson, Geoffrey D.; Trinci, Anthony P. J. (2020), 21st Century Guidebook to Fungi, doi:10.1017/9781108776387, ISBN 9781108776387
  8. ^ Smith, Sally A; Read, David (2008), "2 - Colonization of roots and anatomy of arbuscular mycorrhizas", Mycorrhizal Symbiosis (Third ed.): 42–90, doi:10.1016/B978-012370526-6.50004-0, ISBN 9780123705266