Unexpected allies: desert moss and fungal partners
Mosses are among the toughest vegetative organisms on Earth. They cling to Antarctic ice, cling to alpine rock faces, and even survive the scorching sands of the world’s hottest deserts. For decades, scientists assumed that such resilience meant mosses could thrive without any mutualistic assistance from other life forms. A recent study from the University of California, Riverside, challenges that long‑held view by revealing traces of mycorrhizal fungi embedded within the tissues of desert‑dwelling mosses.
Why the discovery matters
Mycorrhizal fungi are celebrated helpers for most terrestrial plants. They extend the plant’s root network, draw up nutrients from the soil, and in exchange receive sugars produced through photosynthesis. This exchange underpins countless ecosystems. Mosses, however, lack true roots and instead use hair‑like structures called rhizoids. Because of this anatomical difference, researchers previously believed that mosses operated independently of fungal aid. The new evidence suggests that even these primitive pioneers may have forged a subtle partnership, reshaping our understanding of early land‑plant evolution.
Exploring the barren biocrusts
Graduate researcher Kian Kelly ventured into the searing landscapes of Southern California, traversing the Mojave and Colorado deserts. There, he sampled thin biological crusts—complex, often overlooked layers composed of bacteria, algae, fungi, and mosses that bind the soil surface together. Kelly’s mission was to determine whether arid conditions influence the fungal communities residing inside moss cells.
Back in the laboratory, the collected moss fragments were finely ground, and DNA sequencing was employed to hunt for fungal signatures. The results were striking: mycorrhizal DNA appeared in abundance, and the fungal profiles inside the moss differed markedly from those in the surrounding substrate. This pattern indicates that the fungi are not merely accidental contaminants but are likely integrated members of the moss micro‑environment.
Microscopic proof of interaction
DNA alone was not enough to convince Kelly. He stained the moss tissue with a blue dye that highlights fungal structures and examined the samples under a high‑resolution microscope. The images revealed intricate, branching hyphae weaving through healthy moss cells. In many instances, these hyphae formed small, tree‑like swellings reminiscent of arbuscules—structures that facilitate nutrient exchange in classic plant‑mycorrhizal relationships.
Because mosses lack conventional roots, the observed arbuscule‑like formations appeared within leaf‑like cells rather than at root tips. The researchers therefore refer to them as “arbuscule‑like” to avoid jumping to definitive conclusions about functional symbiosis.
Implications for evolution and restoration
If future experiments demonstrate a genuine bidirectional flow of carbon and minerals, the finding could rewrite a chapter of evolutionary biology. Mosses share ancestry with the earliest terrestrial plants that colonized land roughly 470 million years ago. A fungal partnership might have been a critical catalyst that allowed those nascent pioneers to endure the harshness of a non‑aquatic world.
Beyond academic intrigue, the discovery holds practical promise. Biocrusts play a pivotal role in stabilizing desert soils, preventing erosion, and sequestering nutrients. Harnessing moss‑fungus alliances could enhance restoration projects aimed at repairing degraded arid landscapes, offering a biologically sustainable toolkit for conservationists.
As the research community digests these preliminary insights, the next steps will involve controlled experiments to track actual nutrient exchange and to decipher how environmental stressors—such as drought or temperature extremes—modulate the partnership.
Source: https://scientias.nl/woestijnmossen-blijken-mogelijk-toch-hulp-te-krijgen-van-schimmels/
