There are 4,000 species and 197 genera in the order Agaricales. Most species thrive on dead, decaying wood, leaves, and soil rich in organic matter.
Agaricus members are distinguished by their fleshy pileus or cap, from the bottom of which several radiating gills or plates grow and produce the naked spores. Their chocolate-brown spores set them apart from other Agaricaceae family members.
Short-lived primary mycelium originates from homokaryotic basidiospores. The primary component of the Agaricus life cycle is the dikaryotic secondary mycelium.
Table of Contents
Classification of Agaricus
The Agaricus genus comprises the regular (“button”) mushroom (Agaricus bisporus) and the ground mushroom (A. campestris), the prevalent cultured mushrooms of the West.
|
Kingdom |
Fungi |
|---|---|
|
Division |
Basidiomycota |
|
Class |
Agaricomycetes |
|
Order |
Agaricales |
|
Family |
Agaricaceae |
|
Genus |
Agaricus |
Life Cycle of Agaricus
The life cycle of Agaricus bisporus is similar to most other mushrooms. This fungal life cycle is cyclical, with adults generating spores that grow and develop into adults which produce their own spores.
Inoculation
It is the first phase of the life cycle of Agaricus bisporus. Eventually, floating mushroom spores will settle on a suitable substrate or surface. The spores advance to the following stage, germination, if the condition in this place is favourable for the mushroom to survive.
Germination of Spores
During this spore germination phase, individual spores produce tiny filaments called hyphae. Closely placed female and male hyphae combine to form fertile mycelium. The mycelium resembles the roots of real plants in appearance.
Expansion of Mycelium
This life cycle phase constitutes the mycelium growth phase, or the phase when the mycelium extends and develops. This expansion happens exponentially. The mycelium strives to decompose organic waste and take in the nutrients released to support its steady growth. Additionally, the mycelium has protective mechanisms to fight competitors and ward off predators.
Hyphal Knot
The mycelium starts to grow and compress into a knot-like formation. During this stage, the mycelium generates many hyphal knots and primordia. This structure produces the ultimate mushroom “body”, called a hyphal knot.
Formation of Primordia
The hyphal knot finally condenses and becomes a primordia. Primordia are essentially smaller versions of adult mushrooms. One mycelium can produce up to a thousand tiny primordia on its surface. Not all primordia develop into the mushroom’s adult “fruiting body.”
Fruiting Body Selection
Only the primordia with the highest growth and productivity rates will mature into fruiting bodies. What we see as a “mushroom” is each individual fruiting body. However, these fruiting bodies are not different organisms, but one organism joined by its mycelium. These fruiting bodies keep expanding and transforming into the mushroom’s adult form.
Mature Fruiting Body
When a mushroom achieves maturity, it concentrates its growth on the fruiting body, which it will later use for reproduction. The mushroom keeps expanding and transforming until it fully matures and begins to spore. The fruiting body portion of the Agaricus bisporus mushroom is what we consume.
Spore Release
During this last stage of the life cycle, the adult fruiting body releases a significant amount of tiny spores into the environment. The gill structure on the bottom of the mushroom’s cap releases the spores. In the inoculation stage, these spores ultimately settle on a suitable surface and restart the life cycle.
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