Fistulina hepatica
This genome was sequenced as a part of the large-scale multi-genome JGI CSP Saprotrophic Agaricomycotina Project (SAP), which focuses on the diversity and evolution of decay mechanisms, organismal phylogenetic relationships, and developmental evolution. A large collaborative effort led by PI of this project, David Hibbett (Clark University) aims for master publication(s) of the SAP data analysis. Researchers who wish to publish analyses using data from unpublished SAP genomes are respectfully required to contact the PI and JGI to avoid potential conflicts on data use and coordinate other publications with the SAP master paper(s).
Fistulina hepatica is a wood-decaying member of the Agaricales that grows as a saprotroph or a weak parasite on hardwoods1. It is commonly known as the “beefsteak fungus” or “ox tongue”, because of the color and texture of the edible fruiting body. Fistulina hepatica is reported to cause a brown rot (a form of decay in which lignin is not appreciably degraded). JGI has produced whole genome sequences of other brown rot species in the Polyporales (e.g., Postia placenta, Fomitopsis pinicola, and Wolfiporia cocos), Boletales (Coniophora puteana and Serpula lacrymans) and Gloeophyllales (Gloeophyllum sepiarium)2, but this is the first genome of a brown rot species in the Agaricales. Therefore, the F. hepatica genome will provide insight into a unique origin of a decay strategy that allows certain fungi to circumvent lignin while attacking the carbohydrate portions of plant cell walls. Moreover, phylogenetic studies3 have shown that the genus Fistulina is in a group of fungi that also includes another JGI-sequenced wood decayer, Schizophyllum commune4, which is noteworthy because it lacks the class II fungal peroxidases that enable typical white rot fungi to degrade lignin. Thus, F. hepatica, together with S. commune and other Agaricales, may illustrate the mechanisms involved in the transition between white rot and brown rot, as well as indicate if there are general patterns in the convergent evolution of brown rot.
Fistulina hepatica is also fascinating from the standpoint of fungal morphology and evolution. Most Agaricales are gilled mushrooms, but the hymenophore (spore-producing structures) of F. hepatica are actually composed of individual tubes that are free from one another. In this regard, they resemble the fruiting bodies of “cyphelloid” fungi, which produce tiny cup- or tube-shaped structures on wood. Some molecular phylogenetic studies have upheld a relationship between Fistulina, Schizophyllum (which itself has a very odd hymenophore, composed of “gills” that are split and curled back on each other) and certain cyphelloid forms, but the grouping has not received strong statistical support. With the application of genome-scale phylogenetic datasets, it should be possible to resolve these relationships with confidence and better understand patterns or morphological and ecological evolution in the Agaricales.
Genome Reference(s)
Floudas D, Held BW, Riley R, Nagy LG, Koehler G, Ransdell AS, Younus H, Chow J, Chiniquy J, Lipzen A, Tritt A, Sun H, Haridas S, LaButti K, Ohm RA, Kües U, Blanchette RA, Grigoriev IV, Minto RE, Hibbett DS
Evolution of novel wood decay mechanisms in Agaricales revealed by the genome sequences of Fistulina hepatica and Cylindrobasidium torrendii.
Fungal Genet Biol. 2015 Mar;76():78-92. doi: 10.1016/j.fgb.2015.02.002
Additional references
Gilbertson, R. L. & Ryvarden, L. North American Polypores. Vol. 1 433 (Fungiflora, 1986).
Floudas, D. et al. The Paleozoic origin of enzymatic lignin decomposition reconstructed from 31 fungal genomes. Science 336, 1715-1719 (2012).
Binder, M., Hibbett, D. S., Wang, Z. & Farnham, W. F. Evolutionary relationships of Mycaureola dilseae (Agaricales), a basidiomycete pathogen of a subtidal rhodophyte. Am J Botany 93, 547-556 (2006).
Ohm, R. A. et al. Genome sequence of the model mushroom Schizophyllum commune. Nat Biotech 28, 957-963 (2010).