The Great Symbioses

Learn · The principle behind the brand's name

The Great Symbioses

We're named Simbiosis for a concrete reason: the Fungi Kingdom is life's great connector. These are the three alliances — documented and measurable — in which a fungus completely changes what a plant, a rock, or an ecosystem can become.

Symbiosis isn't a metaphor we borrowed: it's the biological term for two distinct organisms living together, where the arrangement benefits at least one of them. Among fungi, three of these alliances stand out for how far they reach: the one visible to the naked eye, the one that happens underground, and the one that occurs inside living tissue.

The alliance you can seeLichens

A lichen isn't a species: it's the stable outcome of a partnership. A fungus — the mycobiont, almost always an ascomycete — builds the structure and retains water; a photosynthetic partner — the photobiont, a green alga or a cyanobacterium — makes sugars from light. Together they form a composite organism able to live where neither could survive alone: on bare rock, in the desert, on the tundra.

Mycobiont

The fungus

Gives the lichen its shape, holds water, and shields from the sun. Contributes most of the structure and biomass.

Photobiont

The alga or cyanobacterium

Carries out photosynthesis and feeds the partnership. When it's a cyanobacterium, it also fixes nitrogen from the air.

Third partner · 2016

A basidiomycete yeast

For nearly 140 years the lichen was thought to be a partnership of two. In 2016, Toby Spribille's team found yeasts from a second fungal lineage embedded in the cortex of many lichens, across six continents.

16 days in the vacuum of space

In 2005, samples of the lichens Rhizocarpon geographicum and Xanthoria elegans traveled on the outside of an orbiting satellite, exposed to vacuum, ultraviolet radiation, and cosmic rays. Back on Earth they fully recovered their photosynthetic activity: the fungal cortex acted as a shield. It's one of the most resilient biological associations known.

The alliance undergroundMycorrhizas

Beneath almost every plant, an ancient exchange takes place. Mycorrhizal fungi wrap around and penetrate roots and extend a network of hyphae through the soil far finer than any root. Through that network the fungus delivers water and hard-to-capture nutrients — above all phosphorus and nitrogen — and the plant pays with sugars from its own photosynthesis. The trade is so effective that most of the planet's plants depend on it.

86%
of vascular plants form mycorrhizas; only about 8% do without them entirely
400M+
years perfecting the partnership; it helped the first plants colonize dry land
13 Gt
of CO₂-equivalent that plants channel each year into mycorrhizal mycelium
≈⅓
of annual CO₂ emissions from fossil fuels is what that underground flow amounts to

The honest frontier: careful with the “wood-wide-web”

When these networks connect several plants, people speak of the “wood-wide-web”: the idea of a forest sharing resources through fungal threads. It's a popular image, and it deserves to be held to rigor. A 2023 review led by Justine Karst found that several claims run ahead of the evidence — that these networks are widespread across all forests, that they reliably transfer resources to improve seedling survival, and above all that “mother trees” preferentially send resources and defense signals to their offspring, this last claim without any published, peer-reviewed evidence. The authors also documented a bias toward citing only positive results.

The network exists, and the carbon flow is well measured. But we'd rather tell you what the science holds up, not what sounds better.

The invisible allianceEndophytes

Some fungi live inside a plant's tissues without making it sick. They're called endophytes, and they're not the exception: it appears that every plant in natural ecosystems lives with them. Many pay for room and board by helping the plant withstand drought, heat, herbivores, or pathogens. The landmark review (Rodriguez and colleagues, 2009) sorts them into functional groups based on how they colonize and what they contribute.

2002 · Yellowstone

A grass that withstands impossible heat

Regina Redman and her team showed that the grass Dichanthelium lanuginosum can only tolerate the temperatures of geothermal soils — up to 65°C at the root — thanks to an endophytic fungus, Curvularia protuberata. Without the fungus, the plant doesn't survive there; without the plant, the fungus doesn't thrive either.

2007 · The partner's hidden partner

A virus inside the fungus

Five years later, Luis Márquez and colleagues discovered that the fungus only confers heat tolerance when it carries a specific virus inside it. Remove the virus, and the tolerance is lost; reintroduce it, and it returns. A virus, inside a fungus, inside a plant: three organisms that, in that soil, depend on one another.

Why this opens LearnSymbiosis is the backbone

Fauna, Flora, Funga. For a long time the Fungi Kingdom was the one school biology didn't know where to place, and yet it's the one that connects the others: it mediates between rock and alga in the lichen, between soil and forest in the mycorrhiza, and between the inside and outside of the plant in the endophyte. That's why this page opens the section: almost everything you'll learn here is a different way of looking at the same idea. In nature, very little thrives in isolation.

This idea isn't just biology: it's the brand's stance. You'll find it developed in our manifestos.

Simbiosis ManifestoWhy collaboration, not competition, guides what we doFunga ManifestoThe third kingdom the world is only beginning to nameThe Fungi KingdomWhat it is, and why it's neither plant nor animalThe Science Behind ItHow the evidence backs up what we tell youMycoremediationSymbiosis put to work healing soils and waterThe 8 SpeciesThe mushrooms we work with, one by one

References

  1. Spribille T, et al. Basidiomycete yeasts in the cortex of ascomycete macrolichens. Science. 2016;353(6298):488-492. PMID 27445309. doi.org/10.1126/science.aaf8287
  2. Sancho LG, et al. Lichens survive in space: results from the 2005 LICHENS experiment. Astrobiology. 2007;7(3):443-454. PMID 17630840. doi.org/10.1089/ast.2006.0046
  3. Brundrett MC, Tedersoo L. Evolutionary history of mycorrhizal symbioses and global host plant diversity. New Phytologist. 2018;220(4):1108-1115. PMID 29355963. doi.org/10.1111/nph.14976
  4. Hawkins HJ, et al. Mycorrhizal mycelium as a global carbon pool. Current Biology. 2023;33(11):R560-R573. PMID 37279689. doi.org/10.1016/j.cub.2023.02.027
  5. Karst J, Jones MD, Hoeksema JD. Positive citation bias and overinterpreted results lead to misinformation on common mycorrhizal networks in forests. Nature Ecology and Evolution. 2023;7(4):501-511. PMID 36782032. doi.org/10.1038/s41559-023-01986-1
  6. Rodriguez RJ, White JF Jr, Arnold AE, Redman RS. Fungal endophytes: diversity and functional roles. New Phytologist. 2009;182(2):314-330. PMID 19236579. doi.org/10.1111/j.1469-8137.2009.02773.x
  7. Redman RS, et al. Thermotolerance generated by plant/fungal symbiosis. Science. 2002;298(5598):1581. PMID 12446900. doi.org/10.1126/science.1072191
  8. Márquez LM, et al. A virus in a fungus in a plant: three-way symbiosis required for thermal tolerance. Science. 2007;315(5811):513-515. PMID 17255511. doi.org/10.1126/science.1136237