The genus Amanita is to be respected. This large group of fungi contains not only some of the deadliest mushrooms in the world, but species with mind-altering hallucinating compounds as well as delectable edible species. Needless to say, when you’re foraging for Amanita species, you better know what the heck you’re doing. The fungi featured today is Amanita flavoconia, which is one of the most common species from the genus.
Amanita flavoconia has a wide distribution covering the forest floor wherever you can find its tree hosts. From the Midwest, to the entire east coast of North America you may find this beautiful orange to orange-yellow mushroom. A defining feature are the yellow warts present on its cap that are remnants of what is called a universal veil. The universal veil exists in all Amanita species and acts to protect the immature mushroom from the elements and hungry invertebrates. The most distinguishing characteristic this fungus has are the small yellow granules left by the universal veil at the base of the mushroom.
Small yellow granules left by the universal veil- a distinguishing characteristic of A. flavoconia
Most of these species form ectomycorrhizal (ECM) relationships with trees found all over the world. By encasing the fine roots in sheaths of mycelia, Amanita flavoconia forms a symbiotic relationship with oaks and hemlocks. Its strands of mycelia radiate out its hosts roots, into the environment and act as a highway for nutrients and water. Many of these trees would not survive random harsh conditions without their fungal counterpart.
An artists depiction of A. muscaria and the root-fungal ECM interface
The ancestors of Amanita species decomposed dead plant material instead of teaming up with plants to acquire a steady supply of digestible sugars. Benjamin Wolfe and his team predicted that ECM species of Amanita may have lost functional genes that encode enzymes required for a solitary life as a decomposer. This new research shows that the transition from a saprobic to a mycorrhizal ecology is associated with the loss of two genes that encode for cellulase synthesis. Cellulase is an enzyme that breaks down cellulose, the main form of carbon in organic plant matter. This paper suggests there is a straightforward evolutionary trajectory of ECM fungi, as this has evolved separately 11 times, with all starting as decomposers, only to make the transition to a mycorrhizal lifestyle.
Mycorrhizal species lost enzymes required for decomposition. (Wolfe et. al. 2012)
Amanita flavoconia is an amazing ECM fungus. Its ancestors, with the help of two genes, were able to live from the forest floor using dead plants as a food source. Now, like many other species of Amanita, A. flavoconia relies on living plants to supply its carbon source. The loss of these two genes are irreversible, which has long lasting evolutionary implications. ECM species of Amanita can’t revert back to a saprobic lifestyle, so they will remain as tree mutualists for millennia to come. The descendants of Amanita flavoconia will most certainly be mycorrhizal.