Fungal mitochondrial genomes and genetic polymorphisms

Abstract

Mitochondria are the powerhouses of eukaryotic cells, responsible for ATP generation and playing a role in a diversity of cellular and organismal functions. Different from the majority of other intracellular membrane structures, mitochondria contain their own genetic materials that are capable of independent replication and inheritance. In this mini-review, we provide brief summaries of fungal mitochondrial genome structure, size, gene content, inheritance, and genetic variation. We pay special attention to the relative genetic polymorphisms of the mitochondrial vs nuclear genomes at the population level within individual fungal species. Among the 20 species/groups of species reviewed here, there is a range of variation among genes and species in the relative nuclear and mitochondrial genetic polymorphisms. Interestingly, most (15/20) showed a greater genetic diversity for nuclear genes and genomes than for mitochondrial genes and genomes, with the remaining five showing similar or slower nuclear genome genetic variations. This fungal pattern is different from the dominant pattern in animals, but more similar to that in plants. At present, the mechanisms for the variations among fungal species and the overall low level of mitochondrial sequence polymorphisms are not known. The increasing availability of population genomic data should help us reveal the potential genetic and ecological factors responsible for the observed variations.

Intraspecific diversity of fission yeast mitochondrial genomes

“…Thus, mitochondrial mutation rate in S. pombe is likely to be comparable or lower than the nuclear mutation rate. This is consistent with observations showing that, for fungal species, the mitogenome usually evolves at a rate slower or comparable to that of the nuclear genome in the same species (Sandor et al 2018;Sharp et al 2018). Using 3.12 × 10 −10 substitutions per site per generation as the mutation rate prior, we employed the Bayesian evolutionary analysis software BEAST to perform divergence dating on the S. pombe MT types, excluding the three recombinant MT types (MT15, MT22, and MT23) ( Figure 6A).…”

Discordant evolution of mitochondrial and nuclear yeast genomes at population level

“…S2). This trend is more similar to the pattern observed in animal rather than in fungi (Freel et al 2014;Sandor et al 2018).…”

“…Mitochondrial genome is usually found in high copy number with multiple copies in each organelle (Wiesner et al 1992). Mutation rate of mtDNA is also generally different from the one of the nuclear DNA and it can be significantly lower (plants and fungi) or higher (animals) (Sandor et al 2018). In addition, mtDNA does not follow a mendelian inheritance, since its replication and partition is not directly linked to the cell cycle and transmission is typically uniparental (maternal, in the vast majority of cases), eliminating the potential for sexual recombination.…”

The complete mitochondrial genome of the Chan‐hua fungus Isaria cicadae: a tale of intron evolution in Cordycipitaceae

“…The mitochondrion is one of the few organelles containing their own DNA. Distinct from the nuclear genome, the mitochondrial genome (mitogenome) is usually uniparentally inherited, and there are multiple copies per cell (Sandor et al, 2018). With the emergence of next-generation sequencing techniques over recent years, the number of completely sequenced mitogenomes of eukaryotes including those of fungi has increased dramatically.…”

“…Fungal mitogenomes vary between distantly/closely related species or even between different individuals of a given species (Aguileta et al, 2014;Zhang et al, 2015;Xiao et al, 2017;Sandor et al, 2018). The smallest and largest mitogenomes currently known in the fungi are 12.1 kb in Rozella allomycis in Cryptomycota (James et al, 2013) and 235.8 kb in Rhizoctonia solani in Basidiomycota (Losada et al, 2014) respectively.…”