dikaryons

A dikaryon is a cell or organism of fungi and some algae that contains two separate haploid nuclei. This condition arises from the fusion of two compatible haploid cells, where the nuclei do not immediately fuse. Instead, each nucleus divides independently, and the cell then divides, resulting in daughter cells that each possess two distinct haploid nuclei. This stage is also known as the dikaryotic stage.

Dikaryotic hyphae are a common feature in the life cycle of many basidiomycetes and some ascomycetes. These hyphae are characterized by the presence of clamp connections, which are specialized hyphal outgrowths that ensure the proper distribution of nuclei during cell division, maintaining the dikaryotic state. The dikaryotic stage can persist for a significant portion of the fungal life cycle, often forming the bulk of the mycelium.

The significance of the dikaryotic state lies in its role in sexual reproduction. When conditions are favorable, the two haploid nuclei within a dikaryotic cell finally fuse to form a diploid nucleus. This diploid nucleus then undergoes meiosis, producing four haploid spores, which are genetically diverse due to the recombination that occurred during meiosis. The dikaryotic stage is thus a bridge between the haploid and diploid phases, allowing for genetic recombination before the production of new haploid individuals.