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Basidiomycota

life science Maturity 5-7 Next article →

Basidiomycota is a massive division within the kingdom Fungi. Members of this group are called basidiomycetes. They belong to a larger subkingdom known as Dikarya. This subkingdom also includes the Ascomycota fungi. Together, these two groups are often called the "higher fungi."

Fungi Sexual reproduction cycle
Fungi Sexual reproduction cycle

The Basidiomycota are incredibly diverse. They include familiar mushrooms, puffballs, and stinkhorns. They also include bracket fungi, jelly fungi, and boletes. Some species, like rusts and smuts, are important in plant biology. Others, like the yeast Cryptococcus neoformans, can be pathogens in humans.

Most basidiomycetes are filamentous fungi. They grow using a network of tiny threads called hyphae.

Fungus cell cycle-en
Fungus cell cycle-en

While most use hyphae, some members are yeasts. A key way to identify these fungi is through their unique reproductive process. They reproduce sexually by forming specialized, club-shaped cells called basidia. These basidia usually produce four external spores known as basidiospores. In some species, these spores are ballistic, meaning they are shot into the air. They travel on small, spine-like projections called sterigmata.

Basidium schematic
Basidium schematic

The life cycle of a basidiomycete is quite complex. Unlike animals, they do not have distinct males and females. Instead, they have compatible mating types. Most species use a bipolar or tetrapolar mating system. When two compatible monokaryons (single-nucleus mycelia) meet, they undergo plasmogamy. This is the fusion of their cell cytoplasm. However, the nuclei do not fuse immediately. Instead, they pair up and migrate into each other's hyphae. This creates a dikaryon, which is a mycelium containing two compatible nuclei.

Dikaryons are often much more vigorous than monokaryons. They can live for decades or even centuries. To keep these pairs organized during cell division, many use structures called clamp connections.

Eventually, the long-lived dikaryon produces a fruiting body, or basidiocarp. This structure can be a large mushroom or a small puffball. Inside the fruiting body, the specialized basidia form. Within these basidia, the two nuclei finally fuse in a process called karyogamy. This creates a single diploid cell. Following this, the cell undergoes meiosis. Meiosis is a type of cell division that produces four haploid nuclei. These nuclei then migrate into the four basidiospores. Once released, these spores can grow into new monokaryons to start the cycle again.

Scientists have spent a long time classifying this vast group. In 2007, a coalition of 67 mycologists adopted a major classification system. They recognized three main subphyla: Pucciniomycotina, Ustilaginomycota, and Agaricomycotina. A 2008 estimate suggested the division contains 31,515 species. This includes 1,589 genera and 177 families. By 2020, updates to the system recognized 19 different classes. These include Agaricomycetes, Tremellomycetes, and many others. These modern classifications use DNA sequence data to group fungi more accurately. This is much more precise than older methods based only on physical appearance.

The diversity within Basidiomycota is truly enormous. The Agaricomycotina subphylum contains many "classic" mushrooms, corals, and chanterelles. The Pucciniomycotina subphylum includes many rust fungi and plant parasites. The Ustilaginomycotina subphylum contains most smut fungi. There are also many genera that remain poorly known. Some have not yet been analyzed using DNA technology. These are often labeled as incertae sedis, meaning their exact family placement is uncertain. This shows that much of the fungal world is still waiting to be fully understood.

Studying these fungi provides deep insights into biology. For example, the mushroom Coprinopsis cinerea is used to study meiosis. In this species, meiosis happens synchronously in about 10 million cells. This allows scientists to observe the process in great detail. Research shows that the core genetic program for meiosis is very old. It has been conserved for over half a billion years. Additionally, studying pathogens like Mycosarcoma maydis helps us understand survival. These fungi use meiosis to repair DNA damage. This might help them survive the oxidative defenses of their hosts. Understanding these tiny processes helps us understand the history of life itself.

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File:Fungi Sexual reproduction cycle.png
Fungi Sexual reproduction cycle.png
File:03 01 07 life cycle Basidiomycota basidium (M. Piepenbring).svg
03 01 07 life cycle Basidiomycota...
File:Fungus cell cycle-en.svg
Fungus cell cycle-en.svg
File:Basidium schematic.svg
Basidium schematic.svg
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