Maintenance of high genome integrity over vegetative growth in the fairy-ring mushroom Marasmius oreades

Most mutations in coding regions of the genome are deleterious, causing selection to favor mechanisms that minimize the mutational load over time [1–5]. DNA replication during cell division is a major source of new mutations. It is therefore important to limit the number of cell divisions between generations, particularly for large and long-lived organisms [6–9]. The germline cells of animals and the slowly dividing cells in plant meristems are adaptations to control the number of mutations that accumulate over generations [9–11]. Fungi lack a separated germline while harboring species with very large and long-lived individuals that appear to maintain highly stable genomes within their mycelia [8,12,13]. Here, we studied genomic mutation accumulation in the fairy-ring mushroom Marasmius oreades. We generated a chromosome-level genome assembly using a combination of cutting-edge DNA sequencing technologies, and re-sequenced 40 samples originating from six individuals of this fungus. The ...