plasmogamie

Plasmogamy is a stage in the sexual reproduction of fungi in which the cytoplasm from two compatible haploid cells fuses, while the nuclei from the two cells remain separate. This fusion typically occurs when hyphae of opposite mating types come into contact, or when gametangia fuse, forming a cell or mycelium in which two genetically distinct haploid nuclei share the same cytoplasm, a condition called a dikaryon or heterokaryon.

Following plasmogamy, the nuclei do not immediately fuse. In many fungal groups, plasmogamy is followed by karyogamy, the fusion of the two nuclei to form a single diploid nucleus, which then undergoes meiosis to produce haploid spores. The timing and duration of the dikaryotic stage vary among lineages. In Basidiomycota (such as mushrooms and bracket fungi) and some Ascomycota, the dikaryotic stage can be long-lived and predominate in the mature fruiting body. In many yeasts and other ascomycetes, plasmogamy and karyogamy are closely coupled, with rapid nuclear fusion.

The process is important for genetic recombination and diversity in fungal populations, and the dikaryotic phase allows the coexistence of two genetically distinct haploid nuclei within the same cytoplasm, enabling unique mating interactions and offspring outcomes.

Etymology: the term derives from Greek plasma, meaning “formed thing,” and gamos, meaning “marriage.”