Ecology of arbuscular mycorrhizal fungi

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Biogeography[edit]

Arbuscular mycorrhizal fungi are found in 80% of plant species [1] and have been surveyed on all continents except Antarctica.[2][3] The biogeography of Glomeromycota is influenced by dispersal limitation,[4] environmental factors such as climate,[2] soil series and soil pH [3] and plant community.[2][5] While previous evidence suggests that AM fungi are not specialists on their host species,[6] current studies have indicated that at least some fungi taxa are host specialists.[7]

Response to plant communities[edit]

Since Glomeromycota fungi live inside plant roots, they can be influenced substantially by their plant host and in return affect plant communities as well. Plants can allocate up to 30% of their photosynthate carbon to AM fungi [8] and in return AM fungi can acquire up to 80% of plant phosphorus and nitrogen.[1] The diversity of AM fungal communities has been positively linked to plant diversity,[9] plant productivity[10] and herbivory.[11] Arbuscular mycorrhizal fungi can be influenced by small scale interactions with the local plant community. For example, the plant neighborhood around a focal plant can alter AM fungal communities[12] as can the order of plant establishment within sites.[13]

During invasions of plant species, the AM fungal community and biomass can be drastically altered. In the majority of cases AM fungal biomass and diversity decrease with invasions,.[14][15][16] However, some mycotrophic plant species may actually increase AM fungal diversity during invasion.[17]

Response to environmental gradients[edit]

Arbuscular mycorrhizal fungi vary across many environmental gradients. The tolerance of AM fungi to freezing and drying is known to shift between AM fungal taxa.[18] AM fungi become less prevalent and diverse at higher soil nutrient and moisture concentrations,[19] presumably because both plants allocate less carbon to AM fungi and AM fungi reallocate their resources to intradical hyphae in these environmental conditions.[20] Over the long term, these environmental conditions can even create local adaptation between plant hosts, AM fungi and the local soil nutrient concentrations.[21] Along elevational gradients AM composition often becomes less diverse on mountain tops than at lower elevations, but this effect is driven by the composition of plant species.[22]

Interactions between AM fungi and other plant symbionts[edit]

All symbionts within a plant host interact, often in unpredictable ways. A recent meta-analysis indicated that plants colonized by both AM fungi and vertically transmitted endophytes often are larger than plants independently colonized by these symbionts.[23] However, this relationship is context-dependent as AM fungi can interact synergistically with fungal endophytes inhabiting the leaves of their host plant,[24][25] or antagonistically,[26][27][28]). Similar ranges of interactions can occur between AM fungi and ectomycorrhizal fungi and dark septate endophytes.[29]

Glomeromycota and global change[edit]

Global change is affecting AM fungal communities and interactions between AM fungi and their plant hosts. While it is generally accepted that interactions between organisms will affect their response to global change, we still lack the ability to predict the outcome of these interactions in future climates.[30] In recent meta-analyses, AM fungi were found to increase plant biomass under drought conditions and decrease plant biomass under simulated nitrogen deposition studies.[31][32] Arbuscular mycorrhizal fungi themselves have been shown to increase their biomass in response to elevated atmospheric CO2.[33]

References[edit]

  1. ^ a b Smith, Read, Sally, DJ (2008). Mycorrhizal symbiosis. New York: Academic Press. 
  2. ^ a b c Opik, M; Vanatoa A; Vanatoa E; Moora M; Davidson J; Kalwij JM; Reier U; Zobel M (2010). "The online database MaarjAM reveals global and ecosystemic distribution patterns in arbuscular mycorrhizal fungi (Glomeromycota)". New Phytologist 188: 233–241. doi:10.1111/j.1469-8137.2010.03334.x. 
  3. ^ a b Kivlin, Stephanie; Christine V. Hawkes; Kathleen K. Treseder (2011). "Global diversity and distribution of arbuscular mycorrhizal fungi". Soil Biology and Biochemistry 43 (11): 2294–2303. doi:10.1016/j.soilbio.2011.07.012. 
  4. ^ Lekberg, Y; Koide RT; Rohr JR; Aldirch-Wolfe L; Morton JB (2007). "Role of niche restrictions and dispersal in the composition of arbuscular mycorrhizal fungal communities". Journal of Ecology 95: 95–100. doi:10.1111/j.1365-2745.2006.01193.x. 
  5. ^ Allen, EB; Allen MF; Helm DJ; Trappe JM; Molina R; Rincon E (1995). "Patterns and regulation of mycorrhizal plant and fungal diversity". Plant and Soil 170: 47–62. doi:10.1007/bf02183054. 
  6. ^ Klironomos, John (2000). Host-specificity and functional diversity among arbuscular mycorrhizal fungi. Halifax, Canada: Microbial Biosystems: New Frontiers. Proceedings of the 8th International Symposium on Microbial Ecology. Atlantic Canada Society for Microbial Ecology. pp. 845–851. 
  7. ^ Husband, R; Herre EA; Turner SL; Gallery R; Young JPW (2002). "Molecular diversity of arbuscular mycorrhizal fungi and patterns of associations over time and space in a tropical forest". Molecular Ecology 11: 2669–2678. doi:10.1046/j.1365-294x.2002.01647.x. 
  8. ^ Drigo, B; Pijl AS, Duyts H, Kielak AM, Gamper HA, Houtekamer MJ, Boschker HTS, Bodelier PLE, Whiteley AS, Veen JAV, Kowalchuk GA (2010). "Shifting carbon flow from roots into associated microbial communities in response to elevated atmospheric CO2". Proceedings of the National Academy of Sciences of the United States of America 107: 10938–10942. doi:10.1073/pnas.0912421107. 
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  13. ^ Hausmann, N; Hawkes CV (2010). "Order of plant host establishment alters the composition of arbuscular mycorrhizal communities". Ecology 91: 2333-23343. doi:10.1890/09-0924.1. 
  14. ^ Batten, KM; Skow KM; Davies KF; Harrison SP (2006). "Two invasive plants alter soil microbial community composition in serpentine grasslands". Biological Invasions 8: 217–230. doi:10.1007/s10530-004-3856-8. 
  15. ^ Hawkes, CV; Belnap J; D'Antonio C; Firestone M (2006). "Arbuscular mycorrhizal assemblages in native plant roots change in the presence of invasive exotic grasses". Plant and Soil 281: 369–380. doi:10.1007/s11104-005-4826-3. 
  16. ^ Kivlin, Stephanie; Christine V. Hawkes (2011). "Differentiating between effects of invasion and diversity: impacts of aboveground plant communities on belowground fungal communities". New Phytologist 189 (2): 526–535. doi:10.1111/j.1469-8137.2010.03494.x. 
  17. ^ Lekberg, Y; Gibbons SM; Rosendahl S; Ramsey PW (2013). "Severe plant invasions can increase mycorrhizal fungal abundance and diversity". ISME Journal. 
  18. ^ Klironomos, JN; Hart MM; Gurney JE; Moutoglis P (2001). "Interspecific differences in the tolerance of arbuscular mycorrhizal fungi to freezing and drying". Canadian Journal of Botany 79: 1161–1166. doi:10.1139/cjb-79-10-1161. 
  19. ^ Auge, RM (2001). "Water relations, drought and vesicular-arbuscular mycorrhizal symbiosis". Mycorrhiza 11: 3–42. doi:10.1007/s005720100097. 
  20. ^ Johnson, NC; Rowland DL; Corkidi L; Egerton-Warburton LM; Allen EB (2003). "Nitrogen enrichment alters mycorrhizal allocation at five mesic to semiarid grasslands". Ecology 84: 1895–1908. doi:10.1890/0012-9658(2003)084[1895:neamaa]2.0.co;2. 
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  22. ^ Gai, JP; Tian H; Yang FY; Christie P; Li XL; Klironomos JN (2012). "Arbuscular mycorrhizal fungal diversity along a Tibetan elevation gradient". Pedobiologia 55: 145–151. doi:10.1016/j.pedobi.2011.12.004. 
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  25. ^ Larimer, AL; Bever JD; Clay K (2012). "Consequences of simultaneous interactions of fungal endophytes and arbuscular mycorrhizal fungi with a shared host grass". Oikos 121: 2090–2096. doi:10.1111/j.1600-0706.2012.20153.x. 
  26. ^ Omacini, M; Eggers T; Bonkowski M; Gange AC; Jones TH (2006). "Leaf endophytes affect mycorrhizal status and growth of co-infected and neighboring plants". Functional Ecology 20: 226–232. doi:10.1111/j.1365-2435.2006.01099.x. 
  27. ^ Mack, KML; Rudgers JA (2008). "Balancing multiple mutualists: asymmetric interactions among plants, arbuscular mycorrhizal fungi, and fungal endophytes". Oikos 117: 310–320. doi:10.1111/j.2007.0030-1299.15973.x. 
  28. ^ Liu, QH; Parsons AJ; Xue H; Fraser K; Ryan GD; Newman JA; Rasmussen S (2011). "Competition between foliar Neotyphodium lolii endophytes and mycorrhizal Glomus spp. fungi in Lolium perenne depends on resource supply and host carbohydrate content". Functional Ecology. 910-920 25. 
  29. ^ Reininger, V; Sieber TN (2012). "Mycorrhiza reduces adverse effects of dark septate endophytes (DSE) on growth of conifers". PLOS ONE 7: 1–10. doi:10.1371/journal.pone.0042865. 
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