February 5, 2023

Athens News

News in English from Greece

Oyster mushrooms turned out to be predators that kill the victim with poison

The mycelium of our favorite oyster mushrooms was littered with tiny shoots filled with a powerful neurotoxin that almost instantly paralyzes small worms. Scientists managed to find out what this deadly poison consists of and how it works.

Mushrooms obtain part of the nutrients they need from small animals, primarily roundworms (nematodes), killing them with a powerful nerve poison. Taiwanese scientists were able to determine the composition of this toxin and show how it affects the victim. Information about this Yen-Ping Hsueh and colleagues published on the website science.org.

Nematodes are numerous and widespread throughout the soil, serving as a valuable source of protein for fungi that have mastered predation. Different types of mushrooms find very different ways to hunt them. Some use specialized cells that pierce the victim’s body like a harpoon. Others grow loops that instantly shrink around a worm that accidentally crawls through them.

Unlike these mechanisms, oyster mushrooms rely on “chemical weapons”. They get the bulk of their food by decomposing wood, growing in a dead trunk with thin branching threads (hyphae). However, wood almost does not contain some valuable nutrients, primarily nitrogen compounds. This stimulated the development of predation in oyster mushrooms.

oyster mushroom Pleurotus ostreatus developed a clear strategy. Instead of physically trapping the nematodes, its hyphae produce potent toxins that paralyze the worms within minutes of contact. These toxins cause a massive influx of calcium and systematic cell death throughout the neuromuscular system of nematodes through their externally exposed sensory cilia.

For hunting, microscopic processes are pulled out of the hyphae, at the tips of which spheres filled with toxin are formed. As soon as the worm accidentally touches the toxocysts, the poison is released and begins to act. In a couple of minutes, he paralyzes and kills the victim, the hyphae grow into her body and begin to digest.

Chemical warfare is a common feature of the predator-prey interaction. Predators such as snakes and spiders use modified fangs or radulas to release venom that targets prey. These neurotoxic venoms primarily affect the peripheral nervous system, in particular the neuromuscular junctions, paralyzing prey, although the venoms of some apathetic snakes also cause muscle necrosis mediated by enzyme-dependent damage to the plasma membrane.

Some prey species have evolved specialized structures, such as fish fin spines or plant glandular trichomes, to store venom and secondary metabolites that are used for defense against predators.
In the fungi kingdom, carnivorous fungi exhibit different chemical strategies towards their prey, i.e. nematodes, the most abundant living things in the soil. Nematode trapping fungi produce several volatile compounds that mimic nematode food and sexual signals to lure their prey by mimicking nematode ascarosid pheromones, while creating various trapping devices such as sticky nets and pens, and constricting gripping rings.

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