Rapid Accumulation of Mutations in Growing Mycelia of a Hypervariable Fungus Schizophyllum commune

Abstract

The basidiomycete Schizophyllum commune has the highest level of genetic polymorphism known among living organisms. In a previous study, it was also found to have a moderately high per-generation mutation rate of 2×10−8, likely contributing to its high polymorphism. However, this rate has been measured only in an experiment on Petri dishes, and it is unclear how it translates to natural populations. Here, we used an experimental design that measures the rate of accumulation of de novo mutations in a linearly growing mycelium. We show that S. commune accumulates mutations at a rate of 1.24×10−7 substitutions per nucleotide per meter of growth, or ∼2.04×10−11 per nucleotide per cell division. In contrast to what has been observed in a number of species with extensive vegetative growth, this rate does not decline in the course of propagation of a mycelium. As a result, even a moderate per-cell-division mutation rate in S. commune can translate into a very high per-generation mutation rate when the number of cell divisions between consecutive meiosis is large.

Biocatalyst collection and heterologous expression of sesquiterpene synthases from basidiomycetous fungi: Discovery of a novel sesquiterpene hydrocarbon

“…However, the mutations seemed to have no detrimental effects on the catalytic performance of the STSs. Polymorphic differences might be common in basidiomycetes (Bezmenova et al, 2020; Ide et al, 2012). Several candidates were amplified as immature cDNAs whose open reading frame was shifted by intronic sequences, which were incorrectly spliced; filamentous fungi may sometimes allow a deleterious splicing event (Ide et al, 2012; Nazir et al, 2010; Permana et al, 2022).…”

Reticulate evolution and rapid development of reproductive barriers upon secondary contact pose challenges for species delineation in a forest fungus

“…fuscoviolaceum from the general VCF-file. Relate was then run in --mode All setting the mutation rate to 1e-7 as studies on another rapidly fruiting wood decay fungus found a mutation rate within this order of magnitude 87 . The effective population size (Ne) was set to 10,000, and the recombination map for the Relate analysis was obtained by multiplying the population recombination rate from LDhelmet with 100/(4*Ne), The resulting anc and mut files of each scaffold from the Relate analysis were used to re-estimate coalescence rates and effective population sizes with the Relate script EstimatePopulationSize.sh.…”

Stability across the Whole Nuclear Genome in the Presence and Absence of DNA Mismatch Repair

“…Although outside the scope of this review, whole mitochondrial genome sequencing studies also show age-dependent increases in both point mutations [ 29 ] and large deletions [ 30 ]. The situation is even more extreme in large, long-lived hyphal fungi [ 31 , 32 ] and trees [ 33 , 34 , 35 , 36 , 37 ]. Because they grow outward linearly, lack a dedicated germline, and tend to fruit near their maximum extent, each consecutive fruiting results in more offspring mutations.…”