Poisonous Death Cap Mushroom Clones Itself, Invades California

According to new research, the poisonous death cap mushroom, known as the deadliest in the world, has been spreading throughout California by making clones.

Poisonous "Death Cap" Mushroom Rapid Spread

More than 90% of deaths from mushrooms worldwide are caused by the deadly "death cap" mushroom (Amanita phalloides), an invasive fungus whose fatal amatoxin is responsible.

But it has long been a mystery how it spread from its European roots to colonize every continent but Antarctica.

Mystery Solved: The death cap found in California can fertilize itself and create perfect copies, avoiding the need to mate before dispersing its spores over an unconquered region, according to a study released on January 31 to the preprint server biorXiv.

According to the researchers' preprint, the diversified reproductive strategies of invasive death caps are probably facilitating their quick spread and highlighting the striking similarities between plant, animal, and fungal invasions.

Death caps are ordinary-looking mushrooms.

They have door-knob-sized flowers with a pale green, white, or bronze cap, white gills, and a membrane that resembles a skirt.

The mushroom is said to taste good, so when its lethal effects begin to manifest six to 72 hours later, they frequently come as a shock.

The liver receives the amatoxin poison from the mushroom through the digestive tract, where it sticks to and disables enzymes needed for protein synthesis.

Now that the liver's normal protein production has stopped, rapid organ failure, coma, and death are frequently followed by nausea, diarrhea, and liver failure.

Invasive Mushroom

Death caps grow in the northeast and the mid-Atlantic coast in addition to the cool coastal regions of the West Coast.

However, the poisonous death cap mushroom is not a native of America.

According to Harvard biologist Anne Pringle, as well as other researchers, it traveled to California aboard cork or oak tree seedlings after leaving Europe, NPR reported.

A phalloides spreads throughout Europe by penetrating the roots of European oak trees (Quercus robur) and establishing a symbiotic relationship known as an ectomycorrhiza.

This relationship allows the phalloides to take vital sugars from the roots of the trees in exchange for helping them find water and nutrients and intercept chemical signals from nearby trees.

At the Del Monte Hotel in Monterey, California, in 1938, death caps were discovered emerging from the root system of an ornamental oak tree (Q. suber). The mushroom then jumped to wild California live oaks (Q. agrifolia), native California pines (Q. agrifolia), and even beech, chestnut, birch, spruce, hornbeam, and filbert trees.

The mushroom quickly became more common than it was in its native Europe, and it could soon be found all over the Bay Area and farther up the coast.

Creating Clones of Itself

It has not yet been made clear how exactly it accomplished this feat.

DNA analysis revealed that the death caps reproduced sexually in Europe.

However, the new study's DNA sequences revealed that many of the death caps from California shared exactly the same genetic material with one another and had an asexual reproductive cycle lasting up to 30 years.

According to the researchers, death caps switch to asexual reproduction to establish themselves in new environments before switching back to sexual reproduction upon successful colonization.

According to the study's authors, some of these mushrooms' offspring mate but some do not.

However, the cycle continues to repeat.

With the discovery of this strange capacity for cloning, researchers now have additional queries regarding the fungal invader.

Asexual reproduction was not evident in the samples taken from New Jersey and New York, which may indicate that it only occurs occasionally and in particular settings.

It's also unknown whether all invasive mushrooms use this technique or whether the death cap is the only one that can switch to self-fertilization.

Further study may shed light on the strategy's adoption rates or other peculiar reproduction techniques used by mushrooms, LiveScience reports.