mycorhizal fungi

Richard Winder rwinder at PFC.Forestry.CA
Mon Jan 30 13:21:38 EST 1995


In article <3g5juu$8rf at bud.peinet.pe.ca>, stewart at bud.peinet.pe.ca 
(Paul Stewart) writes:
>Fellow Myconuts:
>	Has anyone a contact for research or info regarding mycorhizal fungi?
>Specifically, I'm looking for any attempts to culture them.  My idea is 
>to try extracts of the companion roots or surrounding soil as additives 
>to agar and similar additives to the spawn mix (grain, wood chips, sawdust).
>	I have successfully grown mycelium cultures of Boletus edulis 
>(king bolete), chanterelles, and Suillus luteus (slippery Jack), all of 
>which are native to PEI, but not reliably plentiful enough to wild 
>harvest (not crazy about wild harvest anyway).  I've heard from plenty of 
>people that I'm wasting my time, so I'd rather that not be my only reply 
>(Stamets' latest book seems to agree with me).

You are not wasting your time.  Certain boletes (including B. edulis) have 
been reportedly grown in axenic culture.  Ditto for morels.  It will take a bit
of imagination and research to overcome the technical problems in a way that
would be economically feasible, though.

>	Anyone with ideas to share please e-mail me or reply to this 
>group.  I'll continue to be willing to share any of my own findings.  I 
>have already identified some necessary trace elements from soil 
>containing Chanterelle mycelia.  I just took samples from the mycelial 
>layer, the grass root zone, and below this, followed by similar samples a 
>few feet away.  The mycelia seemed to accumulate manganese, boron, and 
>calcium in significant quantities.  Any comments.....?

Just some really crazy ideas, with apologies out there to those who may have
already considered these things...

For culture of mycorrhizal mushrooms in general, I wonder if some of
the issues to contend with are:

1) Intactness/size of mycelium

Let's face it- B. edulis can get pretty big.  Many of these mushrooms probably
need to achieve a certain mycelial size before they start pumping all that
water and nutrients into a fruiting body (hence the use of deep dish agar
cultures to produce Boletus spp.)

2) Water relations

If the medium dries out before a fruiting body can get going, it will abort.
Proper water flow could also be involved in wicking away staling compounds or
inhibitory compounds such as phenolics.

3) Nutrient flux

A clear source/sink flow of nutrients may need to be established.
A disruption of this flux might also be necessary for fruiting.

4) Inhibitors

Some seeds need ample water to leach away inhibitors linked with dormancy- it
wouldn't be shocking to find them in fungi.  At any rate, closed systems
accumulate waste products, inhibitors, etc. much more readily than open ones.
Hence the incorporation of orange slices in successful Armillaria spp. 
mushroom culture (I think that the ascorbic acid/Vitamin C/antioxidant helps 
the fungus deal with accumulated phenolic compounds and other inhibitors- 
but watch that pH!).

5) Templates

The orange peels described above also provide a good hunk of cellulose which
probably acts as a nutritious growth template.

6) Photoperiod/hormones

The B. edulis in my front yard (no, you can't have my home address!) always
fruit exactly on Canada day (July 1) with the Amanita muscaria 2 days behind.
The involvement of photoperiod might be direct, or indirect (plant hormones,
etc.).

7) Nutrient base

Approximating more closely the amino acids and sugars present in a tree root 
which are being exported to the mycelium might be a big help.  Pectins,
suberin, and various cell wall constituents  might help.  Maybe you also
need phosphorylated compounds, membrane compounds (glycolipids, DNA fragments,
etc.), or triggers like c-AMP to indicate a "living" presence- who knows. 

8) Microbes

Chantrelles and truffles apparently have a good deal of bacteria incorporated
into their sporocarps, which may indicate symbiosis with other microbes as well
as plants.  It might be that bacterial cell wall components could be
incorporated into the medium to avoid the contamination problems posed
by these symbionts, which are usually facultative saprobes.  If the bacteria 
produce iron-abosorbing ionophores which the fungus can use, this might be
another thing to look into.  Various microbes (bacteria, yeasts) may not be
true symbionts, but may aid in sporocarp formation by providing competitve
stress or an environmental cue.

Still ready to grow boletes commercially?	-RSW

  RICHARD WINDER                    Title: Research Scientist
  Canadian Forest Service           Phone: (604) 363-0773
  Victoria, B.C.                    Internet: RWINDER at A1.PFC.Forestry.CA



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