Algae living inside fungi: How land plants first evolved

Algae living inside fungi: How land plants first evolved
Credit: Michigan State University

Scientists think that green algae are plants water-living ancestors, but we are not sure how the transition to land plants happened.

New research from Michigan State University, and published in the journal eLife, presents evidence that algae could have piggybacked on fungi to leave the water and to colonize the land, over 500 million years ago.

"Fungi are found all over the planet. They create symbiotic relationships with most land plants. That is one reason we think they were essential for evolution of life on land. But until now, we have not seen evidence of fungi internalizing living algae," said Zhi-Yan Du, study co-author and member of the labs of Christoph Benning, and Gregory Bonito.

Researchers selected a strain of soil fungus and marine alga from old lineages, respectively Mortierella elongata and Nannochloropsis oceanica.

When grown together, both organisms form a .

"Microscopy images show the aggregating around and attaching to fungal cells," Du said. "The algal wall is slightly broken down, and its fibrous extensions appear to grab the surface of the fungus."

Surprisingly, when they are grown together for a long time—around a month—some algal cells enter the fungal cells. Both organisms remain active and healthy in this relationship.

This is the first time scientists have seen fungi internalize a eukaryotic, photosynthetic organism. They call it a photosynthetic mycelium.

"This is a win-win situation. Both organisms get additional benefits from being together," Du said. "They exchange nutrients, with a likely net flow of carbon from alga to fungus, and a net flow of nitrogen in the other direction. Interestingly, the fungus needs physical contact with living algal cells to get nutrients. Algal cells don't need physical contact or living fungus to benefit from the interaction. Fungal , dead or alive, release nutrients in their surroundings."

"Even better, when nutrients are scarce, algal and grown together fend off starvation by feeding each other. They do better than when they are grown separately," explained Du.

Perhaps this increased hardiness explains how algae survived the trek onto land.

"In nature, similar symbiotic events might be going on, more than we realize," Du said. "We now have a system to study how a can live inside a non-photosynthetic one and how this symbiosis evolves and functions."

Both organisms are biotech related strains because they produce high amounts of oil. Du is testing them as a platform to produce high-value compounds, such as biofuels or Omega 3 .

"Because the two are more resilient together, they might better survive the stresses of bioproduction," Du said. "We could also lower the cost of harvesting algae, which is a large reason biofuel costs are still prohibitive."


Explore further

New biofuel production system powered by a community of algae and fungi

More information: Zhi-Yan Du et al, Algal-fungal symbiosis leads to photosynthetic mycelium, eLife (2019). DOI: 10.7554/eLife.47815
Journal information: eLife

Citation: Algae living inside fungi: How land plants first evolved (2019, July 24) retrieved 17 August 2019 from https://phys.org/news/2019-07-algae-fungi-evolved.html
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Jul 24, 2019
Some scientists think this whole evolution thing is a bunch of nonsense. You gotta at least give those evolutionists credit for keep trying. But they keep coming back with comments like "we are not sure how the transition happened...." as in this article. They will never understand something that didn't happen.

Jul 24, 2019
How does this symbiotic relationship compare to that in lichens? They're not re-inventing THAT wheel, are they?

Jul 25, 2019
Some scientists think this whole evolution thing is a bunch of nonsense. You gotta at least give those evolutionists credit for keep trying. But they keep coming back with comments like "we are not sure how the transition happened...." as in this article. They will never understand something that didn't happen.


Some low IQ loonies believe that a sky fairy created the universe, life an everything... in 6 days to boot, in spite of all evidence to the contrary. The low IQ loonies have been fed this nonsense by con artists that have been milking their kind for millenia. We pity those low IQ loonies, but we know that they will never try to understand the wonders of the universe and will forever hide behind the "goddidit" fantasy.

Oh, you poor, gullible, low-IQ loony.

Jul 25, 2019
How does this symbiotic relationship compare to that in lichens? They're not re-inventing THAT wheel, are they?


Actually, I believe they are talking about a different mechanism, also symbiotic. In lichen the algae and fungus exist separately, but here they are referring to a symbiotic relationship where the algal cells enter in to the fungal cells.

The title is highly misleading, though. This probably has nothing to do with the evolution of plants, which are a completely different kind of eucaryotic cells.

Jul 25, 2019
Actually, I believe they are talking about a different mechanism, also symbiotic. In lichen the algae and fungus exist separately, but here they are referring to a symbiotic relationship where the algal cells enter in to the fungal cells.

The title is highly misleading, though. This probably has nothing to do with the evolution of plants, which are a completely different kind of eucaryotic cells.


Thank you! I was thinking that might be the case but I value your learned opinion.

Jul 29, 2019
Not quite endosymbiosis, but a model for how such an evolution can start.

The title is highly misleading, though. This probably has nothing to do with the evolution of plants, which are a completely different kind of eucaryotic cells.


Well, algae are "plants" too - plants is a paraphyletic concept, like fishes (does not include land living tetrapods) or dinosaurs (originally did not include birds), and have evolved several times; the same goes for "algae".

The title seems legit, it is a model for how land plants can have evolved and why fungal relationships are so numerous (since the plant/algae modify when in contact with fungus).

Jul 29, 2019
Torbjorn? You wouldn't happen to play Overwatch, would you?

Aug 11, 2019
Thanks for sharing this interesting article. I never considered that it was possible for algae living inside fungi. Is there more information regarding lowering the cost of harvesting algae since it has a great impact on cost-ineffectiveness for biofuel production?

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