I put this page together a year or so ago after looking at Laspilitas Nurserey's web site describing the fungal web that seems to have so much to do with the way plants operate. I was just trying to teach myself how it all works. Some of the quoted sources' URL's  aren't there anymore. I assembled the page in regular msword with hyperlinks and am just now saving it as html.
Paul Furman 12-23-99

INDEX

I. Mycorriza
 

II. Endomycorriza
 

III. Ectomycorriza [VAM]

IV. Ericoid mycorriza
 

V. Survival Strategies
 
 

Mycorrhiza Frequently Asked Questions
 
 
 
 

I. Mycorriza –"fungus root"

Different types of mycorrizal types and their habitats:
 
 

The fungus gives a chemical signal to the root to grow when they are connected and the root also tells the fungi when it is safe to grow. Plants won’t go into vigorous growth without a mycorrizal connection (or fertilizer.)

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II. Endomycorriza -inside the root -Vesicular Arbuscular Mycorriza [VAM] [VA]

Cicumventers -type "K" strategy deciduous or dormant

Shrubs, grasses, perennials, bulbs, most things

Vesicular Arbuscular

Won't grow in raw soil, must have roots to attach to, plant a cover crop on stockpiled topsoil. (ecto also?) Fresh cut roots will allow transplanting

Tobacco crop rotation is needed to maintain diversity of species and resilience

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III. Ectomycorriza [ECTO] -covering the root tips & grouted between cells but not inside plant’s cells.

cool – moist –plant gives up to 80% sugar gift to the host

Oaks, Pines require it but are flexible about which species

Stress tolerators -type "S" strategy and "K", not "R" Ruderal

Trees, shrubs:

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IV. Ericoid mycorriza –(ericacious) Heather family root fungus

Peat bogs, acid soils, 100 % organic, thick duff, add 50-70% peat moss for simulating in gardens.

Nutrient stress: low nitrogen and especially phosphorus.

Generally found on the edge of moisture.

High elevation manzanita is partly to weakly ericoid, gautheria, kalmia, ledum leucothoe, pyrolla, Rhododendron, red huckleberry
 
 

All orchids steal nutrients from conifers, especially the non-chlorophyll non-photosynthetic types Heather family is closely related to orchids
 
 

Douglas fir & birch have been shown to share sugars through the mycorrizal grid.

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V. Survival Strategies

Stress Tolerators "S"
 
 
 
 

A. Ruderal "R"

B. Circumventers "K"

C. Stress Tolerators"S"
 
 

VI. Fertilizer

Fertilizer provides the plants nutrients causing it to cut off association with the fungus, leaving it to die. Mycorrizal fungi survive by maintaing control of limited nutrients.

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http://sunsite.unc.edu/london/orgfarm/Pesticide-Education/Sustainable-Agriculture/symbiosis/fungi-mycorrhizae.faq

-from a FAQ list about fungi
 
 

4. Mycorrhizae and their significance

Mycorrhizae are mutualistc associations between plant roots and fungi.

These beneficial symbioses are ubiquitous in nature and almost all

plant species have some form of mycorrhizal association with fungi.

Herbaceous and tree species, both deciduous and coniferous, are

receptive to infection by mycorrhizal fungi. A few crop plants in the

cabbage family (Brassicae) and goose-foot families (Chenopodiaceae)

are less likely to be mycorrhizal except in very stressful

environments low in soil fertility.
 
 

The types of mycorrhizal fungi and the associations they form with

roots are varied. These associations are classified as endotrophic

(fungus inside roots) or ectotrophic (fungus outside the root forming

a sheath of mycelium over the root surface). Still other associations

in some forest trees are ectendotrophic or combinations of these

types. Other forms exist such as the unique mycorrhizal association

with Rhizoctonia-like fungi inside the roots of orchids.
 
 

The endomycorrhizal fungi generally associated with the roots of

agricultural crops are in the Class Zygomycetes to which the common

black bread mold belongs. However, these fungi are obligate symbionts

and cannot be cultivated outside the living roots of plants. Their

colonization is internal to the root and cannot be seen without

staining and microscopy. The common genera are Glomus and Gigaspora

producing large, distinctive azygospores that can be wet sieved from

the soil. These spore germinate in the presence on plant roots and

infect the outer cortical cells. However, the cell is not killed and

although the plant cell wall is penetrated the cell membrane is not

disrupted. The endomycorrhizal fungus produces a highly branched

hyphal structure called an arbuscule within the plant cell by

invaginating its cell membrane. This infection creates an absorptive

structure with a very high surface area of transfer for nutrients

between the plant and the fungus.
 
 

The plant usually has few root hairs in this area and the fungus

provides the intimate contact with the soil through fine extraradical

hyphae which extend several millimeters beyond the root. This

extensive hyphal network enhances absorption of water and nutrients,

particularly phosphorus, and promotes growth of the plant. In exchange

for the phosphorus which is transferred to the plant, the fungus

obtains sugars and other organics vital to its growth and

reproduction. These exchanges have been verified by various

histochemical studies and the use of nutrients labelled with

radioisotopes. As the association begins to senesce, the fungus

produces vesiculate storage bodies on and within the root cells and

produces the distinctive asexual spores. Sexual reproduction has

rarely been observed for these fungi.
 
 

The ectomycorrhizal fungi are in the Class Basidiomycetes and Class

Ascomycetes, the fungi that we usually identify as wild mushrooms in

various forest environments. Genera such as Russula, Lactarius,

Laccaria, Amanita, Boletus, and Tuber (truffle) or Cenococcum (false

truffle) to name a few, are all ectomycorrhizal. They are facultative

symbionts of the roots of forest trees and their colonization can seen

with the naked eye. These fungi can be cultivated in the laboratory on

special nutrient media. They have limited saprophytic abilities and

prefer to grow in association with plant roots. The mutual benefits

are similar to those described for the endomycorrhizae. The

ectomycorrhizal fungus froms a sheath or mantle of densely packed

hyphae on the surface of tree roots. This mantle is often black or

brightly colored. The mantle is connected to highly branched hyphae

that penetrate the root and grow between but not into the bost cells.

This network of hyphae (hartig net) forms the absorptive structur that

is the site of nutrient exchange. The sheath is connected to

extraradical hyphae that permeate the soil and absorb water and

nutrients for the ectomycorrhizal root.
 
 

Other benefits of mycorrhizal associations that are of interest to

plant pathologists include biological control and the various growth

promotion effects that enhance establishment of plants in the field.

Mycorrhizal roots are generally more drought tolerant. The general

vigour of mycorrhizal plants makes them more tolerant of limited root

loss due to diseases. Another mechanism of biocontrol by mycorrhizal

fungi is the competiton for nutrients and space on the root against

the pathogenic soilborne fungi. The ectomycorrhizal fungi have the

added advantage of being able to produce antibiotic substances that

inhibit the fungal pathogens. Prior colonization by mycorrhizal fungi

may also stimulate the root to produce natural defensive wall

structures and chemicals (chitinases and phytoalexins) that protect

the root from attack by pathogens. The mycorrhizosphere (or area on

and around the root of mycorrhizal roots) also contains communities of

helpful microorganisms including fungi and bacteria that are anta

onistic to pathogens and that solubilize nutrients such as rock

phosphate.
 
 

There is a great potential for the use of mycorrhizal fungi and

associated microorganisms as inoculants especially in the production

and protection of high-value greenhouse-grown crops or transplanted

vegetable crops such as tomatoes and other bedding plants. The

challenge is to produce the inoculum of endomycorrhizal fungi that

cannot as yet be grown in artificial culture. Various stabilization

and embedding or pelleting methods are being developed for coating

seeds or inoculating potting media with root fragments and spores.

These have been adapted from the technology used to develop Rhizobium

inoculum for leguminous crops. Peat-based potting media with

mycorrhizal inoculum are being developed in Canada by companies such

as Premier Peat Moss (Riviere-du-Loupe, Quebec). The production of

ectomycorrhizal inoculum for forest nurseries based on solid-substrate

fermentation and amendment of potting media is well-underway in The

United States of America and Australia.
 
 
 
 

OTHER RELATED WEB LINKS
 
 
 
 

WFCC World Data Center for Microorganisms (WDCM) provides a

comprehensive directory of culture collecions, databases on microbes

and cell lines, and the gateway to biodiversity, molecular biology and

genome projects. Try the STRAINS - fungi Search Interface

http://www.wdcm.riken.go.jp/
 
 

STRAINS - fungi Search Interface

http://www.wdcm.riken.go.jp/htbin/STRAINS-fungi.pl
 
 

California State University Biological Sciences WWW Server. The

purpose of this server is to consolidate existing WWW Biological

Science teaching and research resources and to create and distribute

original multimedia resources for the teaching of biology. Try the

FUNGI-related links

http://130.17.2.215/index.html
 
 

FUNGI-related links

http://arnica.csustan.edu/FU.html </A>
 
 

Symptoms of Disease

http://www.gov.ab.ca/%7eagric/htmldocs/600/63000101.html
 
 

Root Biology and Mycorrhiza Research Group

http://www.uoguelph.ca/CBS/Botany/roots.html
 
 

Mycological Resources on the Internet

http://muse.bio.cornell.edu/taxonomy/fungi.html
 
 

Symptoms of Disease - Alberta Agriculture, Food and Rural Development
 
 

Root Biology and Mycorrhiza Research Group, Department of Botany,

University of Guelph, Ontario, Canada
 
 

Mycological Resources on the Internet - Cornell University
 
 
 
 

Allen, M.F. (Editor). 1992. Mycorrhizal Functioning: An Integrative

Plant-Fungal Process. Chapman and Hall, London
 
 

Harley, J.L. and Smith, S.E. 1983. Mycorrhizal Symbiosis. Academic

Press, London.
 
 

Pfleger, F.L., and Linderman, R.G.(Editors) 1994. Mycorrhizae and

Plant Health. American Phytopathological Society Press, St Paul, MN .
 
 

Metting, F.B. Jr.(Editor). 1993. Soil Microbial Ecology: Applications

in Agricultural and Environmental Management. Marcel Dekker, Inc. New

York.
 
 

Last Revised: Thursday, August 10, 1995
 
 
 
 

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