Fungi in the Environment

What fungus uses a “shotgun” approach to survive?

Scientists now believe that the Salem witch hunts of 1692 may have initially been caused by an infestation of a microbiological poison: The fungus Claviceps purpurea, commonly known as rye smut that produces the poison ergot. When ingested, this poison produces symptoms similar to those exhibited by the girls who accused others of being witches in Salem. Historians and biologists have reviewed environmental conditions in New England from 1690 to 1692 and have found that conditions were perfect for an occurrence of rye smut overgrowth, as the weather was particularly wet and cool. In addition, rye grass had replaced wheat as the principal grain because wheat had become seriously infected with wheat rust during the cold and damp weather. The symptoms of ergot poisoning include convulsions, pinching or biting sensations, and stomach ailments, as well as temporary blindness, deafness, and muteness.

The fungus Pilobolus spends much of its life around a cow pasture—specifically in cow dung. They are decomposers, breaking down organic matter as it feeds on the dung. But in order to survive, the fungus needs to get into the cow’s dung: First, the cow eats the spores of the Pilobolus while it grazes; the tough spores pass through the animal’s digestive tract, and when the animal excretes, the fungus is there, ready to grow.

But in order to spread, the fungus has evolved a way to shoot its spores into the grass to make it easier for the cows to grab and ingest. The fungus’s stalk contains spore at the top, and as water pressure in the stalk increases, the tip eventually explodes— “shooting” the spores away at around 35 feet (10.8 meters) per second—at a height that can jump over cows and land up to 8 feet (2.5 meters) away. From there, the cows eat the spores that land in the grass, starting the cycle all over again.


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