One of the references in “Planet Fungi” caught my attention. Well, actually what caught my eye was
“While primitive plants already used cellulose to form their cell walls, the transition to terrestrial life demanded a sturdier framework. This led to the development of lignin, a tough and almost unbreakable polymer that provides plants with their backbone.
However, lignin posed a massive clean-up challenge when plants die.
Before the saprotrophic fungi, lignin remained impervious to decomposition. Plant matter accumulated as peat, eventually giving rise to the coal seams we unearth today.
Enter the saprotrophic fungal pioneers – 290 million years ago, in the twilight of the Carboniferous period, an ancestral white rot fungus emerged, armed with an enzyme capable of breaking down the seemingly unbreakable.”
The reference for this is:
>>Wood is a major pool of organic carbon that is highly resistant to decay, owing largely to the presence of lignin. The only organisms capable of substantial lignin decay are white rot fungi in the Agaricomycetes, which also contains non–lignin-degrading brown rot and ectomycorrhizal species. Comparative analyses of 31 fungal genomes (12 generated for this study) suggest that lignin-degrading peroxidases expanded in the lineage leading to the ancestor of the Agaricomycetes, which is reconstructed as a white rot species, and then contracted in parallel lineages leading to brown rot and mycorrhizal species. Molecular clock analyses 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.<<