Lichen Trinity Discovered

It has long been thought that lichens consist of a single fungus species and a single photosynthetic partner, usually a species of green algae or cyanobacteria. However, a new study of macrolichens (the most abundant kind) from six continents has found that many of these organisms also feature specific basidiomycete yeasts in their cortex, meaning the symbiosis involves not one but two fungi! This groundbreaking research, published in Science, changes the paradigm of lichen biology and may explain several lingering mysteries surrounding these organisms. Scientists have struggled with the taxonomy of the group, as lichens with seemingly the same alga and fungus often look vastly different from each other. These morphological variations may be explained by differences in the overlooked cortex yeast, and researchers hope genetic analyses will now give insight into the muddled classifications. Additionally, although these organisms are ubiquitous in nature, scientists have had difficulty growing them in laboratory settings. Algae and fungi routinely fail to form the expected lichens in the lab, and this is likely due to the fact that the needed yeasts were missing.