basidiomycetes_germline

Summary

In sexually reproducing organisms, the germline controls trans-generational inheritance of genetic material. The timing of germline specification is crucial for mutation transmission: a late specification, close to gamete production, can allow somatic mutations to enter the germline, whereas an early specification serves as a barrier to their transmission. In fungi, it is thought that the germline may be defined late in development since they can regenerate mycelia from single cells. In this study, we investigated the transmission of somatic mutations in the mushroom-forming fungus Marasmius oreades. Over seven years, we collected mushrooms, separated sterile tissues (stipe, cap) from fertile tissues (lamellae, spores), and identified new mutations through whole-genome sequencing. We observed a clear distinction between tissue types: sterile and fertile tissues from different mushrooms carried unique sets of mutations. This finding suggests that cell fate in mushroom-forming fungi is predetermined, with the germline destined for spore production already defined within the mycelium. Additionally, the germline exhibited fewer mutations than sterile tissues, indicating a lower mutation rate. Our results uncover new insights into fungal development and suggest that germline sequestration may be more common across multicellular life than previously thought.