In The Mushroom Cultivator, by Paul Stamets and JS Chilton, the authors include a section on mushroom genetics. It's very good, assuming that I knew very little about genetics to begin with. I'll try and explain my understanding of it. Mushroom mycellium is asexual, producing my meiosis (or mitosis, whichever one is asexual) it fills up a niche, and when the nutrients have run out, and the conditions are right, it produces a fruitbody. The fruitbody is still asexual, but the spores produced by it are not. Spores germinate, creating monokaryotic mycellium. This type of mycellium is not capable of producing mushrooms, so it must connect with another compatible mycellium to create dikaryotic mycellium, which is capable of fruiting. This is where the gene/hyphae interchanging takes place. The kicker is that out of all the spores from a mushroom germinating, about 1/4 are capable of mating with eachother, even though they are non-compatible, ie incest. These matings produce mycellium that LOOKS dikaryotic, but is actually uncapable of producing mushrooms. Sorry if I've only told you stuff that you know, or I didn't answer your question, but I read the chapter yesterday and had to reply. Anyone know if I've got it right? Bobbo
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NearEnd, this is the best I can do, now, after reading a few biology texts: Each hypha (mycelium cell) may contain two nuclei from genetically distinct sources, after contact and gene-swapping with another hypha. Cytoplasm is also exchanged between the adjoined cells. Subsequent mycelial growth (mitotic cell division) does not alter this state in any way. It is only when basidia (spore-producing cells) are formed in a mushroom (from hyphal tip cells) that fusion of the nuclei occurs, producing four spores from the two nuclei. So, meiosis occurs only in the gill area of a fruiting body. Some types of mushroom can, as well, achieve meiosis within one organism, fusing two nuclei from the one parent spore, but I could not determine if our genus of interest was among them. Now, I have to assume that any haploid hyphae that interact with a neighboring hypha have some way of preventing hyphae of their own organism (lets say on the other side of the mycelial clump) from picking up a differently nucleated playmate, and so on. And that leads to my basic question: Can primordia (and fruiting bodies) of one parent mycelium form which contain nuclei from more than two parent sources?
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