Literature Review: Fungal Evolution

by Carl Strang

Fungi work behind the scenes for the most part, but they have played, and continue to play, essential roles in Earth’s ecosystems. That important work began a long time ago.

We most often notice fungi at the brief times when they grow spore-dispersing structures.

We most often notice fungi at the brief times when they grow spore-dispersing structures.

Floudas, Dimitrios, et al. 2012. The Paleozoic origin of enzymatic lignin decomposition reconstructed from 31 fungal genomes. Science 336:1715-1719.

Comparative genomic and molecular clock analyses in fungi “suggest that the origin of lignin degradation might have coincided with the sharp decrease in the rate of organic carbon burial around the end of the Carboniferous Period.” In other words, the immense volumes of Paleozoic coal accumulated because fungi had not yet evolved the ability to decompose wood down into its nutritious chemical components. After they did so, much less wood survived to become coal.

Wolfe BE, Tulloss RE, Pringle A (2012) The Irreversible Loss of a Decomposition Pathway Marks the Single Origin of an Ectomycorrhizal Symbiosis. PLoS ONE 7(7): e39597. doi:10.1371/journal.pone.0039597

They looked at the genetics of nutrition in Amanita fungi, and found that their mutualistic partnerships with vascular plants are obligate. The fungi have lost two genes that once allowed them to decompose organic matter in the soil, so that they now depend upon their mutualistic partners for carbon. This study refers to another very important ecological role many fungi play. They form partnerships with many green plants, channeling in soil minerals in exchange for other goodies. As the authors point out, this trade no longer is an option: the partners can’t survive without it.

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