Arbuscular mycorrhizae Endomycorrhizae Ericoid mycorrhizae Orchid mycorrhizae http://www.microbiologyprocedure.com/mycorrhizae/ectomycorrhizae.html Ectendomycorrhizae
(ECM) Ecto- means outside and in the case of ECM it means the fungal hyphae do not normally penetrate into healthy cortical cells of the plant Mantle (m): fungal sheath on the root surface like a glove Hartig net (n): hyphae between root epidermal and cortical cells (c)
Mantle Hartig net Primary phloem Primary xylem Endodermis Cortical cell Hypha (non-mycorrhizal textbook root c.s.)
are morphologically distinctive http://cropsoil.psu.edu/sylvia/morpho
Most ECM fungi are Basidiomycota (e.g. Amanita, Amanita, Boletus, Cantharellus, Cortinarius, Entoloma, Entoloma, Gomphidius, Hebeloma, Hygrophorus, Inocybe, Lactarius, Paxillus, Rhizopogon, Russula, Scleroderma, Scleroderma, Suillus, Thelephora, Tomentella) Peterson, R.L., et. al. 2006, Kwantlen.ca/Horticulture
Some ECM fungi are Ascomycota (e.g. Cenococcum, Muciturbo, Sphaerosporella, and, as shown, Tuber) Peterson, R.L., et. al. 2006 And a few ECM fungi are Zygomycota (in the genus Endogone and Glomus)
ECM predominantly occur on the roots of tree species in the Pinaceae (ECM only), Fagaceae, Betulaceae, Salicaceae (may also form AM, a type of endomycorrhizae).
Hyphae emanating from the mantle may extend several centimeters in to the surrounding soil Hyphae are small diameter and long and therefore have a much greater surface area than do roots or root hairs Hyphae access soil micropore space to reach more water and nutrients in dry conditions Hyphae may also maintain hydraulic conductivity with the soil as it dries and shrinks
Root hair Hypha of Cenococcum geophyllum >2000 hyphae may emanate from one mycorrhiza 4 m of hyphae in 1 ml of soil Peterson, R.L., et. al. 2006 Trappe and Vogel, 1977
Hyphae may combine to from mycelial strands or rhizomorphs May grow several meters and transport water and nutrients (especially Nitrogen, Phosphorus, Potassium) to the roots
ECM may protect against root pathogens Species of certain ECM fungi (e.g. Lactarius, Cortinarius, and Hygrophorus) produce antibiotic substances Some of these antibiotics are antifungal on Rhizoctonia solani, Pythium debaryanum and Fusarium oxyporum The mantle may exclude nematodes http://www.microbiologyprocedure.com/mycorrhizae/resistance-to-plant-diseases-by-ectomycorrhiza.html
Pratylenchus penetrans Peterson, R.L., et. al. 2006 http://plpnemweb.ucdavis.edu
Abiotic Disorders & ECM Nutrient deficiency symptoms less likely on ECM plants Leaf scorch symptoms less likely as many ECM fungi can grow at water potentials well below the permanent wilting point of the plant Toxic metals (Fe, Al, Mn, S) or excessive nutrients are more likely filtered out on ECM plants Smith, S.E. and. D.J. Read. 1997
Photo Credits (images with no URL shown) Peterson, R.L., et. al. 2006. Mycorrhizas: Anatomy and Cell Biology Images. NRC Research Press. Roth, A.L. 1990. Mycorrhizae of Outplanted Conifers. M.Sc. Thesis. University of British Columbia. 298 p Roth, A.L. Kwantlen Plant Database (www.kwantlen.ca/hort)
Selected References Smith, S.E. and. D.J. Read. 1997. Mycorrhizal Symbiosis (2nd Ed.). 605 pp. Academic Press, San Diego and London Whipps, J.M. 2000. Microbial Interactions in the Rhizosphere. J. Exp. Botany. V. 52: 487-511 Zhang, R.Q. et. al. 2010. Forest Pathology (on-line) 28 JUL 2010