plazmogamie

Plazmogamie is a term used in mycology to describe the fusion of cytoplasm from two compatible fungal mycelia or gametes during sexual reproduction. During this process, the plasma membranes merge and cytoplasmic contents mix, but the nuclei from the two parents do not immediately fuse. The resulting cell contains two genetically distinct nuclei in the same cytoplasm, a condition known as a dikaryon, or in some cases a heterokaryon if more than two nuclei are present. Plazmogamie is typically followed by karyogamie, the fusion of nuclei, which produces a diploid nucleus that subsequently undergoes meiosis to generate haploid spores.

In many fungi, plazmogamie follows chemical signaling between compatible mating types using pheromones; hyphal fusion occurs at the point of contact, sometimes within specialized structures such as fruiting bodies. The timing between plazmogamie and karyogamie varies; in basidiomycetes, the dikaryotic stage can be long-lived and is essential for fruiting-body development, while in ascomycetes, plazmogamie and the formation of ascogenous hyphae with dikaryotic compartments are common. Eventually karyogamie occurs in a dedicated organ (ascus or basidium) after nuclear pairing.

Compatibility systems known as heterokaryon incompatibility or vegetative incompatibility exist; genetically incompatible hyphae may restrict plazmogamie or trigger cell death to prevent genetic exchange.