The secondary mycelium of a basidiomycete is shown here. (a)...

The secondary mycelium of a basidiomycete is shown here. (a) How would you describe its cells? (b) What stage of its life cycle is it in? $(c)$ Draw the next steps in this stage of its life cycle.

Key Concepts

Dikaryotic Mycelium

In basidiomycetes, after the fusion of compatible monokaryotic hyphae, the resulting secondary mycelium becomes dikaryotic, meaning that each cell contains two distinct nuclei. This stage is crucial for sexual reproduction, as the paired nuclei remain separate until later processes allow for their fusion.

Clamp Connections

Clamp connections are small, bridge-like structures found in the hyphae of many basidiomycetes. They function to ensure that during cellular division each resulting cell maintains one nucleus from each parent, preserving the dikaryotic state, which is essential prior to the formation of reproductive structures.

Life Cycle of Basidiomycetes

The basidiomycete life cycle is characterized by alternating stages of growth and sexual reproduction. The secondary mycelium, which is dikaryotic, eventually gives rise to fruiting bodies where nuclei fuse within specialized cells called basidia. This is followed by meiosis and the production of basidiospores, continuing the cycle.

Fruiting Body and Basidia Formation

Once the dikaryotic mycelium develops into a fruiting body, specialized structures called basidia are formed. Within these basidia, karyogamy (nuclear fusion) occurs, leading to a transient diploid phase which quickly undergoes meiosis to produce haploid spores. This process is key to the sexual reproduction and genetic diversity of basidiomycetes.

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