Scientists breathe new life into 250-year-old fungal spores

Mushrooms had been collecting dust in a museum for a quarter of a millennium. Still, the researchers managed to germinate two specimens.

In 1770, Carolus Linnaeus, an 18th-century botanist considered the spiritual father of modern taxonomy, classified the mushroom Podaxis. It is a rather curious fungus that thrives in harsh environments. The copies have now been kept in a museum for 250 years. But in a new study Remarkably, the researchers were able to breathe new life into the mushrooms.

Podaxis
Podaxis has fascinated scientists and explorers for centuries. However, little research has been done to date. This is partly because the fungus does not occur in the most common places. “One of the most remarkable things about Podaxis is where it is located,” said researcher Benjamin Schantz-Conlon in an interview with Scientias.nl. “It grows in the desert (which is not a pretty obvious place for large mushrooms) as well as on termite mounds – another remarkable place.” In addition, it happens seasonally and at varying times. Scientists wishing to take a closer look at the fungus are therefore faced with a rather undisciplined challenge: where is it found?

250 year old mushrooms
In a new study, a research team turned to an unconventional sampling location: museum collections. They asked several museums – including the Linnaean Society of London and the Danish Natural History Museum – various fungal spores. In the end, they managed to collect over 200 specimens from all continents except Antarctica. The pieces were between 2 and 250 years old.

Specimens from the South African National Mushroom Collection in Pretoria. Image: Benjamin Schantz-Conlon

The researchers had a great challenge ahead of them. Because would they be able to revive copies on the shelves for 250 years? Surprisingly, the researchers finally succeeded in germinating two specimens of Podaxis collected in the 1770s and classified by Linnaeus. “It was really amazing growing these mushrooms, which we knew had been processed by the eminent scientist Linnaeus, in our lab,” says Schantz-Conlon. “It’s amazing that we were successful. This is more than we could have imagined when we first started to germinate fungal spores.

Unique?
This means that the fungal spores of Podaxis can be regenerated even after a quarter of a millennium. The results therefore reveal the extraordinary ability of Podaxis spores to remain viable even during prolonged periods of drought. Additionally, it suggests that the fungus can live in an inactive stage for centuries, but can sprout again as soon as conditions allow. How unique is this feature really? “We can’t say for sure,” says Schantz-Conlon. “I have never heard of anyone who succeeds in germinating such ancient fungal spores. But at the same time, I also haven’t heard from people who have tried it at all. If it is possible to have more fungal spores, museum collections could represent a great source of biological and historical diversity that can be used in modern research projects.

Differences
The researchers seized the unique opportunity to closely study the Podaxis species. “It allowed us to conduct experiments and examine genomes in a way that would have been impossible with dried specimens,” says Schantz-Conlon. Researchers compared Podaxis mushrooms that grow in deserts with those found on termite mounds. Because what we do know is that the two species are genetically and physiologically different from each other. For example, the species that lives on termite mounds has a smaller genome and reduced resilience to stressful conditions. This is because it probably benefits from its association with termites.

Podaxis growing on a termite mound. Image: Wilhelm de Beer

“In addition, Podaxis can form large mushrooms up to 30 centimeters,” says Schantz-Conlon. “But from what we can see, only the species of Podaxis that grow on termite mounds seem to form fungi. This would indicate a degree of specialization; something that is often associated with a change in the genome and physiology of an organism. These changes can be caused by various selective pressures associated with the new lifestyle, as well as changes in the size of the population. “

Medication
But that’s not the only interesting thing about the study. Because it is possible that the fungus could one day be used as medicine. “We have discovered that Podaxis is capable of producing a wide variety of chemicals,” said Schantz-Conlon. “Linnaeus said the strain can be used to treat“ cancerous ulcers. ”So I think it could be very interesting to further study the potential of Podaxis for the development, for example, of antibiotics or other useful chemicals.

Termieten
At the same time, the researcher hopes to better study the curious relationship between the fungus and termites in the future. “We know that certain species of Podaxis are specialized and apparently also dependent on termites,” said Schantz-Conlon. “But we don’t know if their presence actually benefits the termites themselves.”

What the study unequivocally shows is that a huge source of knowledge is stored in museum collections. So it may well be that other specimens will also be used in the future to answer important scientific questions. Because these museum pieces on display may not be as dry and dead as they might appear. “I know we’ve talked about this before, but I was really surprised that we were able to germinate spores of the species described by Linaeus,” says Schantz-Conlon. “I am always amazed at the quality of the genomes that we were able to generate and the experiments that we were able to carry out.”