Let me also throw my 2 cents into this can of worms...
Jef said:
I am kind of thinking out loud here to see what I think I know and I'm asking you to use your knowledge to help me test mine.
1.) Let's say I make an agar plate from a sample from a single fruitbody (clone). This should be the result of two mycelia, each genetically half complete, meeting, forming clamp connections and forming a genetically whole mycelium (two that become one) that then was able to fruit.
2.) If I make a plate from spores from the same mushroom from above, many spores may germinate and many pairs of spores may mate (form clamp connections), so I may have some mycelia still half complete and incapable of fruiting and many genetically complete mycelia, some capable of fruiting, some not.
3.) If I grow this culture out on a substrate, some unique mycelia will like the substrate better than others and prosper. There still may be many unique mycelia growing there. Some half complete mycelia may meet a compatible (contam) partner to form a sexually complete mycelium that now has two separate parents. This culture may be one of those that prospers.
4.) I fruit the substrate. I expect a poor yield from this process because many unique mycelia have consumed the substrate.
Some of these are half complete mycelia and cannot fruit, and some complete mycelia that are incapable of fruiting, and some are just slower fruiting mycelia, that are not fruiting yet, and some could fruit, but not under the conditions I am supplying.
I have experienced having P. ostreatus and P. eryngii fruiting from the same substrate, so why not five different strains of the same species ?
The two monokaryotic mycelia from single spores, which fuse through anastomosis, exchange nuclei and then form a dikaryotic mycelium with clamp connections between the hyphal cells are just the simplified standard example, used to make it easier to understand the fungal life cycle. In reality, most species show a different behaviour. Some already have two or more nuclei per spore, others never show clamp connections or do not even need a second nucleus to fruit. Usually more than two mycelia will fuse, forming a heterokaryotic mycelium, where a large number of different nuclei travel through the hyphal network.
I see a multispore culture as being made of several heterokaryotic hyphal networks rather than dikaryotic strains.
Jef said:
5.) A clone form a single fruitbody should represent a single genetically complete mycelium, the one that liked the substrate, could cope with all the competition and was the one to fruit soonest given the conditions I provided. An isolate, Isolate 5, I will call it.
We are back to 1.) above now.
5a.) The next flush from the same substrate may be from an entirely different strain (and probably is), one that fruits later, for example. It could be cloned to agar. Isolate 5a.) doing step 1.) above, again.
6.) Isolate 5, and 5a. having now lived alone for a period of time will have had existing genes turned on or off by it's new experience. This is described as an epigenetic process of changed acetylation states.
Although each might not have tried to stifle their rival while "growing out" on the original plate and later the substrate, they may (for the first time) do so now if meeting again on an agar plate now.
At my stage of life, I have become accustomed to and have grown to like living alone, without competition, strife or rival. Forcefully rejecting that which I would have formerly tolerated is part of that same curve. If you say that I am conscious and so I can form preferences and make choices, I think you give me too much credit and other creatures not enough.
7.) My understanding of immunity and rejection suggests that an organism recognises molecules as "self" or "not self" and further divides "not self" into harmless and pathogenic.
It may seem unlikely that epigenetic changes would be enough to make two samples of Isolate 5(above) form zones of aversion after being grown apart (for example on different substrates, under different temperatures in different atmospheres etc) but it is by no means impossible. They might consider each other "not self" and form zones of aversion.
A normal "sequence" DNA test would find these samples to be identical, making for a puzzling finding, but more in-depth tests would show that the acetylation (on or off) states of the genes were different between samples.
The lesson could be that no two things are truly the same, but that they only seem to be when we are unable to see them clearly enough.
A culture from a cloned fruitbody is not necessarily made of just one strain, especially when you started from a multispore culture. However, most likely it will consist of strong strains, which outcompeted others.
For the compatibility itself, there must be some kind of (surface molecule based) tissue compatibility, like you say, just like the one that is important for us when receiving an organ transplant.
Epigenetics will definitely play an important role, but the spores of one fruitbody are not genetically identical. Lets say the parent mycelium formed from two spores with different genetics. Now during fruiting when producing spores, meiosis and genetical recombination will happen, resulting in spores with different genetic information. How different should depend on the genetic diversity of the grandparents. This means if you germinate spores from a mushroom that was a hybrid of two very different strains, you should get lots of strains with a high variation of traits and probably lots of incompatible strains. Germinating spores of a mushroom that was inbred and selected for several generations should result in lots of compatible strains, showing very little variation.
Jef said:
Conclusion:
This is why I believe that it is of little profit to do aversion studies with mycelia and better to focus on fruit bodies and spores, which are, usefully, available together.
My two cents (more like two dollars) for today,
Jeff
Sure, these pairing experiments can be a hint, but no hard proof.
Carsten
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