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The world's most poisonous mushroom is now more deadly

Scientists have discovered that species of the "Death Cap" (Amanita phalloides) mushroom in California, responsible for 90% of mushroom-related deaths, are rapidly evolving to produce different and more potent chemicals than their European counterparts.

Agencies and A News LIFE
Published February 21,2026
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The "Death Cap" mushroom, whose natural habitat is Europe but has now spread to America, Africa, and Australia, becoming an invasive species, continues to baffle the scientific community.

New research conducted at the University of Wisconsin-Madison has revealed that the invasive populations in California have genetically transformed into much more "skillful" killers than their European ancestors.


According to the research, the genes responsible for producing toxins in these mushrooms, which arrived in the US in the 1930s, diversified over time. Scientists previously believed that all toxic compounds were produced with a specific "amino acid sequence" (leader sequence).

However, it was found that the mushrooms in California broke this rule, starting to produce much higher amounts of new peptides (protein fragments) that had not been seen before, compared to their European relatives.

This rapid adaptation of the mushroom affects not only the amount of poison but also its spread rate. Experts state that more than 40 mushrooms clustered under a single tree in California forests indicate an "abnormally dense" invasion, contrary to local species.


Although the effect of these newly produced chemicals on humans is not yet fully known, researchers believe this evolution facilitates the mushroom's adaptation to new environments. The change in these mushrooms, where a single one can kill an adult human, makes the extent of the pressure on local ecosystems even more frightening.