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Animation: Life Cycle of a Mushroom

by Pearson
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A mushroom is the spore-producing structure in a group of fungi called the Basidiomycota. Let’s consider its life cycle, beginning with the spores that are produced by the mature fruiting body. The spores are haploid. A spore germinates, dividing by mitosis to produce a filament called a hypha. The hypha grows and branches to produce a filamentous network called a mycelium. The mycelium has a high surface-area-to-volume ratio, which allows the fungus to absorb nutrients efficiently. If the hyphae of different mating types meet, the hyphae may fuse together, forming a cell with a nucleus from each haploid fungus. The cell with two different nuclei is called a dikaryotic cell. The nuclei do not fuse, so the cell is designated n + n. A dikaryotic mycelium forms. The mycelium continues to grow until the right environmental conditions trigger it to grow into a tightly packed, above-ground mass. The mature fruiting body, or mushroom, also consists of hyphae with two nuclei per cell. Each nucleus is still haploid. The mushroom has a cap, in which the spores of the next generation are born. The spores arise on structures called gills on the underside of the cap. The gills consist of hyphae and cells called basidia. The basidia are dikaryotic, containing two nuclei each, one from each mating type. The two haploid nuclei in a basidium fuse to make a diploid nucleus in preparation for meiosis. The diploid nucleus then undergoes meiosis, producing four haploid nuclei. The basidium produces four spores on top of cellular extensions. The nuclei move into these spores. The haploid spores eventually break off from the basidium, and the life cycle repeats.
A mushroom is the spore-producing structure in a group of fungi called the Basidiomycota. Let’s consider its life cycle, beginning with the spores that are produced by the mature fruiting body. The spores are haploid. A spore germinates, dividing by mitosis to produce a filament called a hypha. The hypha grows and branches to produce a filamentous network called a mycelium. The mycelium has a high surface-area-to-volume ratio, which allows the fungus to absorb nutrients efficiently. If the hyphae of different mating types meet, the hyphae may fuse together, forming a cell with a nucleus from each haploid fungus. The cell with two different nuclei is called a dikaryotic cell. The nuclei do not fuse, so the cell is designated n + n. A dikaryotic mycelium forms. The mycelium continues to grow until the right environmental conditions trigger it to grow into a tightly packed, above-ground mass. The mature fruiting body, or mushroom, also consists of hyphae with two nuclei per cell. Each nucleus is still haploid. The mushroom has a cap, in which the spores of the next generation are born. The spores arise on structures called gills on the underside of the cap. The gills consist of hyphae and cells called basidia. The basidia are dikaryotic, containing two nuclei each, one from each mating type. The two haploid nuclei in a basidium fuse to make a diploid nucleus in preparation for meiosis. The diploid nucleus then undergoes meiosis, producing four haploid nuclei. The basidium produces four spores on top of cellular extensions. The nuclei move into these spores. The haploid spores eventually break off from the basidium, and the life cycle repeats.