Fungal Plant Pathogen Discovered in Fossil Collection Identified As the World’s Oldest Disease-Causing Species

The diversity of Kingdom Fungi has gained the interest of experts, and its important role on Earth has been widely acknowledged. Recently, a fungus that attacked other organisms millions of years ago has been unveiled among a collection of fossils.

Earliest Disease-Causing Fungus

Within the Natural History Museum of London is an ancient fungal species hidden in its fossil collections. It was named Potteromyces asteroxylicola, after the famous mycologist Beatrix Potter.

Fossil evidence reveals that Potteromyces asteroxylicola were already diverse in terrestrial ecosystems during the Early Devonian epoch, approximately 407 million years ago. Its discovery sheds light on the early history of fungal disease and the important role fungi played in shaping life on Earth.

The new species was unearthed in microfossil samples from the Rhynie Chert, a significant geological site in Scotland. This region is known for remarkably preserving the Early Devonian community of plants and animals, including fungi and bacteria.

Led by paleontologist Dr. Christine Strullu-Derrien from the Natural History Museum London, a team of researchers analyzed the structures of the fungal species found in the microfossil. They discovered that Potteromyces asteroxylicola has conidiophores, or reproductive structures, with unusual shapes and formations unlike before.

Adding to this mystery is the fact that it parasitized an extinct species of lycopsid plant called Asteroxylon mackiei. The fungus formed a stroma-like structure arising in tufts outside the cuticle on aerial axes and leaf-like appendages of its host. The plant responded by developing dome-shaped growths, indicating that it must have been alive while the fungus attacked. These features in the fungus, together with the reaction of plant tissues, prove that Potteromyces asteroxylicola is a plant pathogenic species.

Other fungal parasites were previously found in Rhynie Chert, but this is the first case of a species that caused plant disease. Additionally, Potteromyces asteroxylicola serves as a reference point from which to date the evolution of different groups of fungi, such as the largest fungal phylum Ascomycota.

Role of Fungi in the Ecosystem

Fungi are a diverse group of multicellular organisms encompassing various life forms. About 100,000 species have already been identified, yet scientists estimate that many species are still yet to be discovered, with the total number ranging from 0.8 to 3.8 million.

Some species of fungi are detrimental to humans, plants, and animals, but they also benefit the overall ecosystem. Due to its vast diversity, the fungi kingdom occupies different niches in nature and is responsible for important functions in the ecosystem.

Fungi can convert nutrients, which are important for plants. Some fungi are decomposers that can break down plant and animal debris, contributing to nutrient cycles and increasing the availability of organic matter in the soil.

As heterotrophic organisms, fungi rely on photosynthetic carbon for energy production. Together with plants, they carry out soil carbon sequestration, where carbon is captured from the atmosphere and stored in the soil.

There are also mushrooms, which are commonly found in the diets of different people around the world. Edible mushrooms are a good source of nutrients, minerals, and proteins. For this reason, they are considered ideal substitutes for meat in vegetarian diets.

Aside from their benefit to the environment, fungi can also benefit human health. Some edible mushrooms possess medicinal properties, while others are known for their antidiabetic and anti-oxidative properties.