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 strong relationship.
"Microscopy images show the algal cells 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.
https://www.sciencedaily.com/releases/2019/07/190723163943.htm
This is the first time scientists have seen fungi internalize a eukaryotic, photosynthetic organism. They call it a photosynthetic mycelium.
"Even better, when nutrients are scarce, algal and fungal cells 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 photosynthetic organism 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 fatty acids.
"Because the two organisms 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."
https://www.fieldmuseum.org/about/press/lichens-are-way-younger-scientists-thought
So, the researchers used the fossils that were available to extrapolate the ages of family trees of lichen-forming fungi and algae. They compared these family trees with ages of fossil plants. The verdict: lichens probably evolved long after complex plants.
“Lichens aren't as old as we thought they were. They're a younger, newer sort of symbiosis and haven't been around forever, covering the earth long before there were plants and animals running around,” says Nelsen.
Unearthing the age of lichens makes it clear that the pattern of modern lichens showing up on rocks before plants doesn’t mean that lichens evolved before plants.
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