Lichens' secret symbiotic threesome

Neat thing about science is that there is always more to learn. When some physicists claimed several years ago that science was at end, that we know everything there is to know, I knew that they didn't know much biology. And since then we have learned new things about physics.

http://www.eurekalert.org/pub_releases/2016-07/aaft-lss071816.php

Public Release: 21-Jul-2016
Lichens' secret symbiotic threesome
American Association for the Advancement of Science

The classical view of lichens - formed by a symbiosis between an algae and a single fungus - is too simple, suggests a new study. The study's results reveal that a third species also contributes to this symbiotic relationship, one of the oldest- and best-known symbioses on Earth. For more than 140 years, scientists have thought that lichens arise from algae or cyanobacteria living among the filaments of a fungus. Recently, it has been suggested that another species may play a role in forming complete, functioning thalli, the leafy or shrubby features of lichens.

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their data revealed 506 genetic signatures reflective of the presence of Cyphobasidium, a type of yeast belonging to the Basidiomycete phylum. Upon broader investigation, the team found other Basidiomycete lineages associated with 52 lichen genera from six continents. Analysis of Cyphobasidium by comparing it to its closest relatives suggests that it may have evolved around the time many lichens did, hinting at a long evolutionary history among it and the other species that make up lichens. When the researchers removed the Cyphobasidium from lichen samples, they discovered dead cells within the cortex of the lichen, suggesting that the yeast's presence is vital to the lichen's health. The yeast cells, it turns out, form the characteristic cortex of the lichen thallus and may be important for its shape.