The early sequestered germline of basidiomycete fungi – spatial distribution, mechanism and generality across the kingdom

The purpose of this project is to investigate how the germline is determined in basidiomycete fungi.

Already in the late 1800s, August Weismann proposed that only germ cells carry heritable information from one generation to the next. Today, it is well known that in unitary animals, the germline is defined early during development.

In plants, fungi and basal metazoans, on the other hand, the current dogma is that the germline is defined much later, meaning that mutations that have accumulated over growth can potentially enter the germline.

We have recent, unpublished, data in hand showing that the fairy ring mushroom Marasmius oreades, sequester its germline early in development.

Our finding challenges the basis of all current evolutionary and mycological knowledge, and calls for further exploration as to both mechanism and breadth of occurrence across the fungal kingdom.

The specific aims of this study are to investigate: I) The spatial distribution of the somatic and germline cell-lines in mycelia of M. oreades, II) The mechanism controlling germline segregation, and III) The prevalence of an early germline sequestration across basidiomycetes. We will use a combination of approaches, including ddPCR and FISH-imaging, bisulphate sequencing and transcriptomics.

As heritable genetic variation forms the basis for adaptive evolution, our project has large implications for evolutionary biology of eukaryotes in general, and for the understanding of fungal biology in particular.