Evolutionary morphology of mushroom-forming fungi

Blogging about Peer-Reviewed ResearchDave Hibbett wrote a great article for Mycological Research that describes the current state of systematics and evolutionary studies of morphology in mushroom-forming Agaricomycete fungi. His article, dedicated to the late, great mycologist Orson K Miller, Jr and entitled “After the gold rush, or before the flood? Evolutionary morphology of mushroom-forming fungi (Agaricomycetes) in the early 21st century” describes the how classification and systematics has changed in the last two hundred years and macromorphology to the more than “108,000 nucleotide sequences of ‘homobasidiomycetes’, filed under 7300 unique names.”

The article contains some beautiful pictures many of which are taken from some of the eminent mycological photographers and mycologists Michael Wood and Taylor Lockwood.

Morphological evolution

One of the main reasons for reconstructing the evolutionary history of the Agaricomycetes group is to understand the evolution of mushroom forms from corals to stinkhorns to chanterelles to boletes to truffles.

How have the morphological forms transitioned evolutionarily? Figure 1[1] demonstrate some of the beautiful transitions in the Hymenophore, or typically the underside of the mushroom cap, from gills or lamellae like a Russula to pores of a Bolete.

Hibbett describes some of the work that has sought to answer what are the relationships of the different groups of mushrooms? The morphology alone does not seem to be sufficient as there is much developmental plasticity and some forms evolve many times. The use of molecular phylogenetics has solidly improved the delineation of the phylogenetic clades. Work from our colleagues next door on understanding how the Rhizopogon false truffle was shown to be derived from the bolete Suillus or work from Vilgalys lab at Duke that the Coprinacea group of fungi were not monophyletic but in fact a family of them are much more closely related to Agarics 1, 2.

The article goes on to discuss major systematics work in the 90s and early 00’s that firmed up the backbone of the Homobasidiomycetes (or Agarics) and established groupings into eight clades. Additional work has shown that there are at least 14 independent and major clades including three which are only recupinate and other that include the previously classified Heterobasidiomycetes with another (Cantharellales) that includes both Homo -and Heterobasidiomycetes. “The remaining eight clades contain only homobasidiomycetes and produce the vast majority of conspicuous mushroom fruiting bodies, as well as cryptic resupinate forms.”

Given the relationships of the species, it is possible then to compare how the morphologies are evolving across the tree. Hibbett describes work using bayesian and ML character evolution to evaluate likely ancestral states and rates of change. In some studies, the morphological forms were coded into binary or sometimes 5 character states and the changes in these states were evaluated under phylogenetic models that estimate the rates of change to different forms. They cite several studies including a recent one on the Boletales that attempt to reconstruct ancestral states and show (perhaps surprising) results like that ancestor the Suillineae was a gasteromycete.

In all it is a very informative review of the current progress that has been made to look at morphological evolution using sophisticated phylogenetic approaches and lots of hard work to characterize and compare forms of Agaricomycotina fungi.

Notes

[1] Unfortunately posting a figure that is from a manuscript to the website would cost $20.23 to obtain permission from the publisher. But you can obtain a copy of the article from the Hibbett lab website.

3 thoughts on “Evolutionary morphology of mushroom-forming fungi”

  1. I never considered the idea of using fungi to study the evolution of form. I am always thinking of insects and gene expression patterns, etc. Aside from sequencing, is anyone studying things like gene expression patterns ?

  2. Ala evo-devo? Working on it… =) Array experiments are being done on Coprinus that will hopefully generate some markers that we can use to try and do analogous experiments. Certainly yeast mother-daughter cell comparisons and yeast/filamentous transitions have been done in dimorphic fungi like Histoplasma, Blastomyces, and Coccidioides. Sexual development and asexual condidation have also been explored both through EST and SSH approaches and microarrays.

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