plant mitochondria

Sloan DB 2015 Using plants to elucidate the mechanisms of cytonuclear co-evolution. New Phytol 205:1040-1046.

• there is an estimated 5000-fold range in documented rates of synonymous nucleotide substitutions in mtDNA
• the specific mechanisms responsible for these apparent changes in mitochondrial mutation rate are yet to be determined
• there are species that diverged within just the last 5–10 Myr and yet differ by c. 100-fold in their synonymous substitution rates
• the rates of sequence evolution in land plant mtDNA are among the lowest observed in any genome
• this pattern is reversed in a small subset of Silene species that have experienced mitochondrial-specific accelerations in synonymous substitution rates
• heterogeneity in mitochondrial substitution rates is by no means unique to plants
• the patterns of substitution rate variation in plant organelle DNA are made even more complex (and interesting) by a number of still unexplained cases in which accelerations have been observed in just a small number of genes, while the rest of the genome remains seemingly unaffected

• evidence of extreme mitochondrial mutation rate accelerations was first reported in plants more than a decade ago
• we still know very little about the mechanistic causes of these changes or their effects on mitochondrial function