Auto-SummaryMultispore cultures involve selfing or inbreeding, which reduces heterozygosity and can lead to less variability, uniform crops, and increased vulnerability to random mutations. While this can result in a consistent crop, it also makes the culture susceptible to recessive mutations, such as the PE mutation, which can cause malformed mushrooms. To maintain a diverse strain, it is recommended to save early prints and slants of the best cultures. Combining spores from different varieties can increase heterozygosity, which can then be selectively selfed to create a new custom variety. Popular classic strains have been stable from multispore for several generations, while new strains can be stabilized within 6-7 generations. Early selection is crucial, as once good genes are bred out, they are lost forever.
Essentially when we use ms we are inbreeding Workman does a great job explaining it nbreeding? Well, it isn't generally good long term, but it is a useful tool for enhancing and isolating certain traits.
Each multispore culture is selfing (breeding with one's self). This doesn't seem to be a problem initially, but sequential multispore cultures reduces heterozygosity. What I mean by sequential multispore is using prints from your current cultivation to start the next cultivation and so on. A better idea is to save prints from your earliest cultivation and use those to preserve your "strain" as long as possible. Cubensis spores should last at least 10+ years if kept cool and dry, but viability drops yearly, so you may need to use large amounts of spores to revive a culture from very old spores.
The loss of heterozygosity means that the spores will produce fruits that show less and less variability from multispore, which sounds fine. You get a nice uniform crop with little variability, so its similar in behavior to a clone. But this also makes your culture vulnerable to random mutations. Random mutations that can be recessive and invisible to the grower. The PE mutation is a good example.
The PE mutation is recessive, so lets say you made a multispore culture from a print, maybe you selected out a single strain on agar or just injected tons of spores into a substrate. You got a crop of nice looking mushrooms and printed some. You gave away all the prints you made and just have one print remaining. Unknown to you, the mushroom you saved the print from was generated by a pair of spores, where one had been hit by a cosmic ray that damaged a key gene necessary for proper cap development. The mushroom looks fine because each of it's cells also contains the nuclei from the other spore with an undamaged gene.
You only have the one print, you want to grow it out again and expect the same results as before. But something is wrong, several mushrooms look like PE, with weird malformed caps. The selfing, or inbreeding has resulted in pairs of the damaged gene appearing in 25% of the generated strains. Many of the mushrooms in the crop look fine, but most of them will also contain the damaged gene. And this is just one trait. More mutations can sneak in over time, almost all of them are bad, some can make the mycelium unable to even fruit.
So save your earliest prints, save slants of your best cultures. Combining the spores of different varieties can increase heterozygosity which can then be selectively selfed to produce a new custom made variety.
I know it's confusing and I probably didn't explain it very well, but maybe I helped.
Workman said: Mushrooom genetics are a little strange since a single mushroom produces spores that can then act as both parents for a new mycelium. Essentially, you are selfing or inbreeding each time you do a multispore grow.
Now consider a wild collection of Psilocybe cubensis with a high heterozygosity. This basically means that most or all of each pair of genes in the mushroom are different from each other. Its the same gene location with the same basic function, but different versions. For example, if there is a single gene for height, you might have a version that gives short mushrooms and a version that gives tall mushrooms. If heterozygosity is high, you have one of each which may result in medium mushrooms unless one of the height genes is dominant.
Now, when you do multispore from a single mushroom you randomly get a mix of all the genes. Sticking to our height gene example, you could get two short copies, two tall copies or one of each. Obviously the strains with two short copies will be short and the ones with two tall copies will be tall.
Lets say we liked the short mushrooms so we saved that one and took a spore print for later. In this example the tall version of the height gene is lost to later generations. There is a net loss of heterozygosity. Over the entire genome the loss is about 50% per generation.
So mathematically we can figure out how many sequential multispore generations we need until the heterozygosity is reduced to an insignificant level and the strain is stable even from multispore.
Starting with a presumably high (~100%) heterozygosity from a wild collection. In reality, the heterozygosity is probably lower than 100%, but its an easy number to start with.
100% wild print 50% 1st generation from wild print 25% 2nd generation from 1st generation print 12.5% 3rd generation..... 6.25% 4th generation..... 3.12% 5th generation..... 1.56% 6th generation..... 0.78% 7th generation.....
You can see that the heterozygosity drops off quickly in the first few generations and is less than 1% after the 6th generation. This highlights the importance of choosing the best traits early on when there are more to choose from. Attempting to isolate traits in well established strains results in only minimal improvements unless spontaneous mutations increase the heterozygosity in a positive way (rare).
In summary:
Popular classic strains in circulation have all been grown well beyond 6 generations and are relatively stable from multispore with little need for isolation.
New strains, from wild material or cross breeding between different strains of the same species, can be stabilized fairly quickly with 6 or 7 generations of sequential multispore grows.
Selection is most important early in the process and if good genes are bred out, they are gone forever. Archiving original or early generation prints is recommended for preserving heterozygosity for later selective breeding. Continuous isolation of a bad strain with hopes of significant improvement is futile.
Does that help?
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