In DepthSYMBIOSIS

A lichen ménage à trois

See allHide authors and affiliations

Science  22 Jul 2016:
Vol. 353, Issue 6297, pp. 337
DOI: 10.1126/science.353.6297.337

You are currently viewing the summary.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

Summary

Lichen isn't much to look at—often just a gray, yellow-green, or garish orange crust on rock or bark. Yet lichens cover up to 6% of Earth's surface, by one estimate. Now, modern genomics is revealing that lichens are startlingly complex. For some 140 years, scientists have understood lichens to be a symbiosis between a fungus, which provides a physical structure and supplies moisture, and a photosynthesizing alga or cyanobacterium, which produces nutrients. Studies of gene activity have now revealed that many lichens are instead a threesome, with two fungi in the mix. The role of the second fungus, a yeast, is uncertain, and some lichen aficionados aren't convinced it is a true symbiotic partner. But others say it's time to throw the textbook understanding of lichens out the window.