Mosses have long been seen as the plant kingdom’s loners, surviving without the fungal partners that help most land plants thrive. A new study has now challenged that idea, finding evidence that fungi can live inside moss cells, a relationship scientists had never documented before.
For decades, researchers assumed mosses were different from most plants. More than 85% of land plants form partnerships with fungi, exchanging sugars for nutrients drawn from the soil. Mosses, with their tiny size and lack of roots, seemed to be the exception.
That assumption is now under scrutiny. In a study published in New Phytologist, researchers found fungal DNA inside moss tissues and even observed fungal structures growing within moss cells. The discovery suggests these ancient plants may be far more connected to fungi than previously thought.
A Clue Hidden In Desert Mosses
The research began with Kian Kelly, a doctoral student at the University of California, Riverside, who was studying biological soil crusts. These living communities include fungi, bacteria, algae, mosses and microscopic animals that share the same patch of ground.
Kelly carried out fieldwork in the Mojave and Sonoran deserts, where temperatures can climb above 100 degrees Fahrenheit. While comparing mosses from different environments, he became interested in whether the fungi associated with them also changed from place to place.
As reported inNew Phytologist, laboratory analyses revealed fungal DNA inside mosses collected from both desert and more temperate regions. Researchers were particularly surprised to find mycorrhizal fungi, which are known for forming close relationships with plants and generally cannot survive without a plant host.
Not Just Fungi From The Surrounding Soil
One of the most interesting findings came when scientists compared fungi living inside the mosses with those found in the nearby soil. The fungal communities did not match. The study found that the species inside the mosses were different from those present in the surrounding dirt, suggesting the relationship was not random.
The team also found that desert mosses hosted different fungal communities than mosses growing in milder climates. That pattern caught the researchers’ attention because it hints that certain fungi may be better suited to particular environments.
“We suspect that certain fungi are more helpful for surviving hotter, drier climates,” Kelly said in a statement published in University of California, Riverside.
The results pushed back against the idea that mosses live entirely on their own. Instead, they point to a more selective association between mosses and fungi.
A Microscope Revealed What Scientists Had Missed
To see exactly where the fungi were located, Kelly stained moss tissues with a blue dye that attaches to fungal structures. Under the microscope, he found branching formations growing directly inside moss cells.
“As soon as I saw that, I knew we had something really interesting,” he added.
Researchers describe how these structures resembled arbuscules, tiny tree-like formations commonly found in the roots of plants that exchange nutrients with fungi. Since mosses do not have roots, the structures appeared in their leaves instead.
The formations were also somewhat different from those typically seen in root systems, making the discovery even more unusual. The press release issued alongside the study notes that researchers believe the structures may indicate a nutrient-sharing relationship, although more work will be needed to understand exactly how it functions.
According to the research, one of Earth’s oldest land plants may not have been as independent as scientists once believed.
