维基百科

用户:Xht88114/沙盒

Epacris pulchella，一种产于东澳的杜鹃花科植物。
长柱杜鹃(Rhododendron occidentale)是一种产于北美西方的杜鹃花菌根共生植物。

杜鹃花菌根是一类和杜鹃花科植物共生的菌根真菌，杜鹃花科植物通常生活在北方针叶林、沼泽和石楠荒原等酸性贫脊的土壤，因此这种共生关系对杜鹃花科植物适应环境十分重要[1]。经过分子钟技术推定这种共生关系大约起源于1.4亿年前[2]。

构造和功能

杜鹃花菌根能在杜鹃花科植物的发根上形成疏松的菌根包附在表皮细胞上，, 穿入皮层细胞的细胞壁并在细胞间产生菌丝圈来将细胞紧紧包附。Ericoid mycorrhizas are characterized by fungal coils that form in the epidermal cells of the fine hair roots of ericaceous species.[3] Ericoid mycorrhizal fungi establish loose hyphal networks around the outside of hair rootsfrom which they penetrate the walls of cortical cells to form intracellular coils that can densely pack individual plant cells.[3] 但并不穿入细胞膜However, the fungi do not penetrate plasma membranes of plant cells. 这种构造只能持续几周，不久后便会崩坏分解。Evidence suggests that coils only function for a period of a few weeks before the plant cell and fungal hyphae begin to degrade.[3]

菌丝圈是真菌用来交换来自土壤的养分和植物光合作用的糖类The coil is the site where fungi exchange nutrients obtained from the soil for carbohydrates fixed through photosynthesis by the plant. 有产生酵素来分解复杂有机物的能力Ericoid mycorrhizal fungi have been shown to have enzymatic capabilities to break down complex organic molecules.[4][5] 这让一些兰花菌根能进行腐生This may allow some ericoid mycorrhizal fungi to act as saprotrophs. 最初的功能是取得有机形式的营养，例如氮，However, the primary function of these enzymatic capabilities is likely to access organic forms of nutrients, such as nitrogen, whose mineralized forms are in very limiting quantities in habitats typically occupied by ericaceous plants.[5]

真菌共生体

 
从Woollsia pungens分离的杜鹃花菌根Gamarada debralockiae。[6]

The majority of research with ericoid mycorrhizal fungal physiology and function has focused on fungal isolates morphologically identified as Rhizoscyphus ericae, in the Ascomycota order Helotiales,[3] now known to be a Pezoloma species.[7]

In addition to Rhizoscyphus ericae, it is currently recognized that culturable Ascomycota such as Meliniomyces (closely allied with Rhizoscyphus ericae), Cairneyella variabilis, Gamarada debralockiae and Oidiodendron maius form ericoid mycorrhizas.[3][8][9][10] The application of DNA sequencing to fungal isolates and clones from environmental PCR has uncovered diverse fungal communities in ericoid roots, however, the ability of these fungi to form typical ericoid mycorrhizal coils has not been verified and some may be non-mycorrhizal endophytes, saprobes or parasites.[11][12][13][14]

In addition to ascomycetes Sebacina species in the phylum Basidiomycota are also recognized as frequent, but unculturable, associates of ericoid roots,[11][12] and can form ericoid mycorrhizas.[15] Similarly, basidiomycetes from the order Hymenochaetales have also been implicated in ericoid mycorrhizal formation.[16]

Geographic and host distribution分布

The ericoid mycorrhizal symbiosis is widespread. 除了南极洲以外皆有分布Ericaceae species occupy at least some habitats on all continents except Antarctica.[17] 有少数杜鹃花科植物并没有和杜鹃花菌根共生A few lineages within the Ericaceae do not form ericoid mycorrhizas, 而是形成其他种类的菌根and instead form other types of mycorrhizas,包含 including manzanita (Arctostaphylos), madrone (Arbutus), and the Monotropoidiae.[3] The geographic distribution of many of the fungi is uncertain, primarily because the identification of the fungal partners has not always been easy, especially prior to the application of DNA-based identification methods.[3] Fungi ascribed to Rhizoscyphus ericae have been identified from Northern and Southern Hemisphere habitats, but these are not likely all the same species. Some studies have also shown that fungal communities colonizing ericoid roots can lack specificity for different species of ericoid plant, suggesting that at least some of these fungi have a broad host range.[13][14]

经济重要性

杜鹃花菌根和多种作物及观赏植物产生共生关系，包含蓝莓、小红莓和杜鹃花属植物，能增加]植物吸收营养的能力。[18]

 
小红莓是一种和杜鹃花菌根共生的作物。
 
Northern highbush blueberries, Vaccinium corymbosum, an ericoid mycorrhizal crop

外部链接

参考资料

  1. ^ Cairney, J. W. G. and A. A. Meharg. 2003. Ericoid mycorrhiza: a partnership that exploits harsh edaphic conditions. European Journal of Soil Science 54: 735–740. doi:10.1046/j.1351-0754.2003.0555.x.
  2. ^ Cullings, K. W. 1996. Single phylogenetic origin of ericoid mycorrhizae within the Ericaceae. Canadian Journal of Botany 74: 1896-1909.
  3. ^ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Smith, S. E. and D. J. Read. 2008. Mycorrhizal Symbiosis, Third Edition. Academic Press.
  4. ^ Cairney, J. W. G., and R. M. Burke.1998. Extracellular enzyme activities of the ericoid mycorrhizal endophyte Hymenoscyphus ericae (Read) Korf & Kernan: their likely roles in decomposition of dead plant tissue in soil. Plant and Soil 205: 181-192.
  5. ^ 5.0 5.1 Read, D. J., J. R. Leake, and J. Perez-Moreno. 2004. Mycorrhizal fungi as drivers of ecosystem processes in heathland and boreal forest biomes. Canadian Journal of Botany 82: 1243-1263.
  6. ^ Midgley, D. J.; Chambers, S. M.; Cairney, J. W. G. Spatial distribution of fungal endophyte genotypes in a Woollsia pungens (Ericaceae) root system. Australian Journal of Botany. 2002, 50 (5): 559. doi:10.1071/BT02020. 
  7. ^ Baral HO and Berbee L. (2006) Hymenoscyphus subcarneus, a little known bryicolous discomycete found in the Białowieża National Park. Acta Mycologia 41:11-20.
  8. ^ Hambleton S, Sigler L (2005) Meliniomyces, a new anamorph genus for root-associated fungi with phylogenetic affinities to Rhizoscyphus ericae (≡ Hymenoscyphus ericae), Leotiomycetes. Studies in Mycology. 53:1-27.
  9. ^ Midgley, D.J., Rosewarne, C.P., Greenfield, P., Li, D., Vockler, C.J., Hitchcock, C.J., Sawyer, N.A., Brett, R., Edwards, J., Pitt, J.I. & Tran-Dinh, N. (2016). Genomic insights into the carbohydrate catabolism of Cairneyella variabilis gen. nov., sp. nov., the first reports from a genome of an ericoid mycorrhizal fungus. Mycorrhiza, 26: 345–352.
  10. ^ Midgley, D.J., Sutcliffe B, Greenfield P & Tran-Dinh, N. (2018) Gamarada debralockiae gen. nov. sp. nov.—the genome of the most widespread Australian ericoid mycorrhizal fungus. Mycorhiza, 28: 379-389.
  11. ^ 11.0 11.1 Allen, T. R., T. Millar, S. M. Berch, and M. L. Berbee. 2003. Culturing and direct DNA extraction find different fungi from the same ericoid mycorrhizal roots. New Phytologist 160:255-272.
  12. ^ 12.0 12.1 Selosse, M. A., S. Setaro, F. Glatard, F. Richard, C. Urcelay, and M. Weiss. 2007. Sebacinales are common mycorrhizal associates of Ericaceae. New Phytologist 174:864-878.
  13. ^ 13.0 13.1 Kjoller, R., M. Olsrud, and A. Michelsen. 2010. Co-existing ericaceous plant species in a subarctic mire community share fungal root endophytes. Fungal Ecology 3:205-214.
  14. ^ 14.0 14.1 Walker, J. F., L. Aldrich-Wolfe, A. Riffel, H. Barbare, N. B. Simpson, J. Trowbridge, and A. Jumpponen. 2011. Diverse Helotiales associated with the roots of three species of Arctic Ericaceae provide no evidence for host specificity. New Phytologist 191: 515-527.
  15. ^ Vohník M, Pánek M, Fehrer J, Selosse M-A (2016) Experimental evidence of ericoid mycorrhizal potential within Serendipitaceae (Sebacinales). Mycorrhiza 26:831–846
  16. ^ Kolarik M, Vohnik M (2018) When the ribosomal DNA does not tell the truth: the case of the taxonomic position of Kurtia argillacea, an ericoid mycorrhizal fungus residing among Hymenochaetales. Fungal Biology 122:1–18
  17. ^ http://www.mobot.org/MOBOT/research/APweb/welcome.html
  18. ^ Scagel, C. F. 2005 Inoculation with ericoid mycorrhizal fungi alters fertilizer use of highbush blueberry cultivars. HortScience 40: 786-794.
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