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"Molecular and morphological systematics of the Polyporales, a highly diverse, poorly documented clade of wood-decaying fungi with biotechnological potential"

Final Report Summary - POLYSYST (Molecular and morphological systematics of the Polyporales, a highly diverse, poorly documented clade of wood-decaying fungi with biotechnological potential)

Basidiomycetes are one of the two largest groups of fungi along with ascomycetes, and include most of the mushroom-type fungi. The main focus in this proposal is one of the largest orders of basidiomycetes, the Polyporales. This project deals with classification (systematics) of the Polyporales. A particular focus is a large genus of polypores or bracket fungi, Rigidoporus.

Rigidorus is not a natural, evolution-based genus in its current form, and during this project we have shown that it needs to be split to at least 11 genera divided in two orders, Hymenochaetales and Polyporales. Some of these genera, such as the yet undescribed Rigidoporus vinctus group, include economically important pests of timber plantations. Another example is Rigidoporus microporus that is one of the most important pests of paleotropical rubber plantations. Rigidoporus microporus is not a Rigidoporus in the strict sense either, and should be included in the genus Leucofomes in stead. We also showed that both of the above-mentioned names have been used for many species, and that only some of them are important as plantation pests. Consequently pest control measures may need to be designed individually for each pest species within those groups.

The genome of the first Finnish fungus was sequenced during this project, coordinated by Dr. Miettinen. The target organism Obba rivulosa is polypore species with the ability to degrade lignin from wood selectively before degrading cellulose. This trait offers potential for biotechnological applications in pulp industry and production of industrial biomaterials. The genome was published by the US DOE Joint Genome Institute in June 2014, and is being analysed in the University of Helsinki through comparative transcriptomics (

A large set of reference specimens for taxonomic and systematic studies was collected during the project from the United States during nine field trips in as many states. Eight papers in scientific journals have been published during the project, and two further manuscripts submitted. In those papers and manuscripts two new genera and ten new species to science are described. As part of those papers 1232 DNA sequences have been submitted in the International Nucleotide Sequence Database. About 4000 herbarium specimens have been collected during the project, and are deposited in the herbarium of the Finnish Museum of Natural History, available for scientific community. Further 500 living cultures of wood-rotting and mycorrhizal fungi collected in North America and the Caribbean are in the process of being deposited to public repositories (HAMBI Helsinki, USDA FPL Wisconsin MD, CBS Utrecht).

This two-year fellowship included a working period of the researcher, Otto Miettinen, in the United States, where Dr. Miettinen worked in the lab of Prof. David Hibbett. During the second year Dr. Miettinen returned to the Finnish Museum of Natural History, University of Helsinki, Finland, to work with Prof. Soili Stenroos. Aided by the fellowship, Dr. Miettinen has become part of the permanent research staff at the Finnish Museum of Natural History, so the project can be considered a success in supporting his career.